**8.1 Introduction**

124 Solar Cells – Thin-Film Technologies

buffer layers is not fully understood, whether it simply prevents short circuits by introducing resistance or also changes the interfacial energetics by introducing additional barriers, and optimization of this interface is a critical need. TCO materials typically used in CdTe solar cells are ITO and FTO. Reports for AZO in CdTe cells are very few. The use of ZnO-based TCOs in CdTe solar sells of superstrate configuration is hampered by its thermal instability and chemical reaction with CdS at high temperatures (550–650°C) typically used for CdTe solar cells fabrication. To resolve this problem, Gupta and Compaan applied low temperature (250°C) deposition by magnetron sputtering to fabricate superstrate configuration CdS/CdTe solar sells with AZO front contacts. These cells yielded efficiency as high as 14.0%. Bifacial CdTe solar cells make it possible to increase the device NIR transmission as the parasitic absorption and reflection losses are minimized. The highest efficiency of 14% was achieved from a CdTe cell with an FTO contact layer. The device performance depends strongly on the interaction between the TCO and CdS films. Later, the same group has noted a substantial In diffusion from ITO to the CdS/CdTe photodiode, which can be prevented by the use of undoped SnO2 or ZnO buffers. Application of TCO as the back contact also allows fabrication of bifacial CdTe cells or tandem cells, which opens a

Copper indium diselenide (CuInSe2 or CIS) is a direct-bandgap semiconductor with a chalcopyrite structure and belongs to a group of miscible ternary I–III–VI2 compounds with direct optical bandgaps ranging from 1 to 3.5 eV. The miscibility of ternary compounds, that is the ability to mix in all proportions, enables quaternary alloys to be deposited with any bandgap in this range. A large light absorption coefficient of >105 cm−1 at photon energies greater than a bandgap allows a relatively thin (few μm in thickness) layer to be used as the light absorber. The alloy systems with optical bandgaps appropriate for solar cells include Cu(InGa)Se2, CuIn(SeS)2, Cu(InAl)Se2, and Cu(InGa)S2. Copper indium–gallium diselenide Cu(InGa)Se2 (or CIGS) has been found to be the most successful absorber layer among chalcopyrite compounds investigated to date. The bandgap is ~1.0 eV for CuInSe2 and increases towards the optimum value for photovoltaic solar energy conversion when gallium is added to produce Cu(In, Ga)Se2. An energy bandgap of 1.25–1.3 eV corresponds to the maximum gap achievable without loss of efficiency. Further increase in the Ga fraction reduces the formation energies of point defects, primary, copper vacancies which makes them more likely to form. Also, a further increase in gallium content makes the absorber layers too highly resistive to be used in solar cells. Therefore, most CIGS devices are produced with an energy bandgap below 1.3 eV, which limits their VOC at ~700 meV. Note that both CIS- and CIGS-based devices are usually dubbed as the CIS technology in the literature. The CIS technology provides the highest performance in the laboratory among all thin-film solar cells, with confirmed power conversion efficiencies of up to 20.1% for small (0.5 cm2) cells fabricated by the Zentrum fuer Sonnenenrgie-und-Wasserstoff–Forschung and measured at the Fraunhofer Institute for Solar Energy Systems, and many companies around the world are developing a variety of manufacturing approaches aimed at low-cost,

high-yield, large-area devices which would maintain laboratory-level efficiencies.

Similarly, TCO layers are generally used for the front contact, whereas a reflective contact material (Ag, frequently in combination with a TCO interlayer, is the most popular one) is needed on the back surface to enhance the light trapping in absorber layers. The optical

variety of new applications of CdTe solar cells.

**7.3 CIGS thin film solar cells** 

Violet and blue enhanced semiconductor photovoltaic devices are required for various applications such as optoelectronic devices for communication, solar cell, aerospace, spectroscopic, and radiometric measurements. Silicon photodetector are sensitive from infrared to visible light but have poor responsivity in the short wavelength region. Since the absorption coefficient of crystal Si is very high for shorter wavelengths in the violet region and is small for longer wavelengths. The heavily doped emitter may contain a dead layer near the surface resulting in poor quantum efficiency of the photoelectric device under short wavelength region.

In order to improve the responsivity of silicon photodiode at the 400-600nm, a novel ITO/SiO2/np Si SINP violet and blue enhanced photovoltaic device (SINP is the abbreviation of semiconductor/insulator/np structure) was successfully fabricated using thermal diffusion of phosphorus for shallow junction, a very thin silicon dioxide and ITO film as an antireflection/passivation layer. The schematic and bandgap structure of the novel SINP photovoltaic device are whown here (Fig.1 and Fig.2). The very thin SiO2 film

Fig. 1. Schematic of the novel SINP photovoltaic device.

TCO-Si Based Heterojunction Photovoltaic Devices 127

In order to learn the optical absorption and energy band structure of ITO film, the transmission spectrum of the ITO film deposited on the glass substrate was measured (Fig.3). The thickness of ITO film is about 700 Å. The average transmittance of the film is about 95% in the visible region and the band-edge at 325nm.While the optical band gap of ITO film is about 3.8 eV by calculation. The reflection loss for ITO film on a texturized Si surface was indicated (Fig.4) from UV to the visible regime, which is much lower than that of Si3N4 film that are widely made by PECVD technology. This shows that ITO film effectively reduced reflection loss in short-wavelength, which is suitable for antireflection

300 400 500 600 700 800 900

n = 2.11 x 1021atom/cm3

ITO film with: Thickness 700

Eg = 3.8 eV

wavelength(nm)

 Si3 N4 ITO

300 400 500 600 700 800

Fig. 4. Comparison of the reflections for ITO and Si3N4 films on a texturized Si surface.

wavelength( nm)

**8.3 Results and discussion** 

**8.3.1 Optical and electric properties of ITO films** 

0

Fig. 3. Transmission spectrum of the ITO film.

20

0

5

10

Reflection(%)

15

20

40

Transmission(%)

60

80

100

Fig. 2. Bandgap structure of the novel SINP photovoltaic device.

not only effectively passivated the surface of Si, but also reduced the mismatch of ITO and Si. Since a low surface recombination is imperative for good quantum efficiency of the device at short wavelength. The ITO film is high conducting, good antireflective (especially for violet and blue light) and stable. In addition, a wide gap semiconductor as the top film can serve as a low-resistance window, as well as the collector layer of the junction. Therefore, it can eliminate the disadvantage of high sheet resistance, which results from shallow junction. Because the penetration depth of short wavelength light is thin, the shallow junction is in favor of improving sensitivity.

#### **8.2 Experimental in detail**

The starting material was 2.0 cm p-type CZ silicon. In the present, two types of shallow and deep junction n-emitters for violet and near-infrared SINP photovoltaic devices were made in an open quartz tube using liquid POCl3 as the doping source. The sheet resistance is 37Ω/口 and 10Ω/口, while the junction depth is 0.35μm and 1μm, respectively. After phosphorus-silicon glass removing, a 2 μm Al metal electrode was deposited on the psilicon as the bottom electrode by vacuum evaporation. The 15~20Å thin silicon oxide film was successfully grown by low temperature thermally (500°C for 20 min in N2:O2=4:1 condition) grown oxidation technology. The 70 nm ITO antireflection film was deposited on the substrate in a RF magnetron sputtering system. Sputtering was carried out at a working gas (pure Ar) pressure of 1.0Pa.

The Ar flow ratio was 30 sccm. The RF power and the substrate temperature were 100W and 300°C, respectively. The sputtering was processed for 0.5h.The ITO films were also prepared on glass to investigate the optical and electrical properties. Finally, by sputtering, a 1μm Cu metal film was deposited with a shadow mask on the ITO surface for the top grids electrode. The area of the device is 4.0 cm2.

#### **8.3 Results and discussion**

126 Solar Cells – Thin-Film Technologies

not only effectively passivated the surface of Si, but also reduced the mismatch of ITO and Si. Since a low surface recombination is imperative for good quantum efficiency of the device at short wavelength. The ITO film is high conducting, good antireflective (especially for violet and blue light) and stable. In addition, a wide gap semiconductor as the top film can serve as a low-resistance window, as well as the collector layer of the junction. Therefore, it can eliminate the disadvantage of high sheet resistance, which results from shallow junction. Because the penetration depth of short wavelength light is thin, the

The starting material was 2.0 cm p-type CZ silicon. In the present, two types of shallow and deep junction n-emitters for violet and near-infrared SINP photovoltaic devices were made in an open quartz tube using liquid POCl3 as the doping source. The sheet resistance is 37Ω/口 and 10Ω/口, while the junction depth is 0.35μm and 1μm, respectively. After phosphorus-silicon glass removing, a 2 μm Al metal electrode was deposited on the psilicon as the bottom electrode by vacuum evaporation. The 15~20Å thin silicon oxide film was successfully grown by low temperature thermally (500°C for 20 min in N2:O2=4:1 condition) grown oxidation technology. The 70 nm ITO antireflection film was deposited on the substrate in a RF magnetron sputtering system. Sputtering was carried out at a working

The Ar flow ratio was 30 sccm. The RF power and the substrate temperature were 100W and 300°C, respectively. The sputtering was processed for 0.5h.The ITO films were also prepared on glass to investigate the optical and electrical properties. Finally, by sputtering, a 1μm Cu metal film was deposited with a shadow mask on the ITO surface for the top grids electrode.

Fig. 2. Bandgap structure of the novel SINP photovoltaic device.

shallow junction is in favor of improving sensitivity.

**8.2 Experimental in detail** 

gas (pure Ar) pressure of 1.0Pa.

The area of the device is 4.0 cm2.

#### **8.3.1 Optical and electric properties of ITO films**

In order to learn the optical absorption and energy band structure of ITO film, the transmission spectrum of the ITO film deposited on the glass substrate was measured (Fig.3). The thickness of ITO film is about 700 Å. The average transmittance of the film is about 95% in the visible region and the band-edge at 325nm.While the optical band gap of ITO film is about 3.8 eV by calculation. The reflection loss for ITO film on a texturized Si surface was indicated (Fig.4) from UV to the visible regime, which is much lower than that of Si3N4 film that are widely made by PECVD technology. This shows that ITO film effectively reduced reflection loss in short-wavelength, which is suitable for antireflection

Fig. 3. Transmission spectrum of the ITO film.

Fig. 4. Comparison of the reflections for ITO and Si3N4 films on a texturized Si surface.

TCO-Si Based Heterojunction Photovoltaic Devices 129

0.0 0.2 0.4 0.6 0.8 1.0

*<sup>D</sup> dV <sup>R</sup>* is derived and shown (in Fig.6). The series resistance

*nk TB J Je* where q is the electronic charge, V is the

*nk TB J Je* , where n = 1.84 and J0 = 5.58×10-6 A/cm2.

Fig. 7. The corresponding logarithmic scale in current with forward bias condition.

the high inversion voltage region, the tunneling current plays a dominant role.

*qV*

In our study, the current-voltage characteristic of the violet SINP device was measured in dark at room temperature (in Fig.5). I-V curves of the devices show fairly good rectifying behaviors. Basing on the dark current as a function of the applied bias, the corresponding

arose from ohmic depletion plays a dominant role when the forward bias is larger than 0.25 V. When the voltage varies within 0.2 V and - 0.2 V, the resistance slightly increases as the diffusion current in the base region. When the inversion voltage increases from - 0.2 to - 0.5 V, the leakage current and the recombination current in the surface layers restrain the increase of the dynamic resistance, which keeps the RD – V curve in an invariation state. In

The plot of ln(J) against V, is shown (in Fig.7), which indicates that the current at low voltage (V < 0.3 V) varies exponentially with voltage. The characteristics can be described by

applied voltage, kB is the Boltzmann constant, n is the ideality factor and J0 is the saturation current density. Calculation of J0 and n from is obtained the measurements (in Fig.7). The value of the ideality factor of the violet SINP device is determined from the slop of the straight line region of the forward bias log(I)-V characteristics. At low forward bias (V< 0.2 V), the typical values of the ideality factors and the reverse saturation current density are

*qV*

The result of calculation is similar to that of the measurement (in I-V curve). By the same calculation method, the ideality factor and the reverse saturation current density of deep junction SINP photovoltaic device are 2.21 and 4.2 × 10-6 A/cm2, respectively. This result indicates that the recombination current *Jr* ≈ exp(*qV*/2*kT*) dominates in the forward current. The rectifying behaviors and the composition of dark current for violet SINP photovoltaic device is better than deep junction SINP device, because the ideality factor of the violet SINP

Voltage(V)

2.26033E-6 6.14421E-6 1.67017E-5 4.53999E-5 1.2341E-4 3.35463E-4 9.11882E-4 0.00248 0.00674 0.01832

**current density(A/cm2**

**8.3.2 I-V characteristics** 

diode resistance defined as <sup>1</sup> ( ) *dI*

the standard diode equation: 0( 1)

Using the standard diode equation 0( 1)

1.84 and 5.58×10-6A/cm2, respectively.

**)**

coating in violet and blue photovoltaic device. Electrical properties of the ITO film were measured by four-point probe and Hall effect measurement. The square resistance and the resistivity are low to 17Ω/口and 1.19×10-4 Ω·cm, respectively, while carrier concentration is high to 2.11×1021 atom/cm3.

Fig. 5. I-V curve of the violet and blue enhanced (shallow junction) SINP photovoltaic device in dark.

Fig. 6. The variation of resistance for SINP violet device via voltage (RD-V curve).

coating in violet and blue photovoltaic device. Electrical properties of the ITO film were measured by four-point probe and Hall effect measurement. The square resistance and the resistivity are low to 17Ω/口and 1.19×10-4 Ω·cm, respectively, while carrier concentration is


Fig. 5. I-V curve of the violet and blue enhanced (shallow junction) SINP photovoltaic device

Surface leakage current


Fig. 6. The variation of resistance for SINP violet device via voltage (RD-V curve).

RD

Tunneling current

G-R current &

0.000

Voltage(V)

Diffusion current

Voltage(V)

Series resistance

0.005

0.010

0.015

0.020

current density(A/cm2

)

0.025

0.030

high to 2.11×1021 atom/cm3.

in dark.

Fig. 7. The corresponding logarithmic scale in current with forward bias condition.

#### **8.3.2 I-V characteristics**

In our study, the current-voltage characteristic of the violet SINP device was measured in dark at room temperature (in Fig.5). I-V curves of the devices show fairly good rectifying behaviors. Basing on the dark current as a function of the applied bias, the corresponding diode resistance defined as <sup>1</sup> ( ) *dI <sup>D</sup> dV <sup>R</sup>* is derived and shown (in Fig.6). The series resistance arose from ohmic depletion plays a dominant role when the forward bias is larger than 0.25 V. When the voltage varies within 0.2 V and - 0.2 V, the resistance slightly increases as the diffusion current in the base region. When the inversion voltage increases from - 0.2 to - 0.5 V, the leakage current and the recombination current in the surface layers restrain the increase of the dynamic resistance, which keeps the RD – V curve in an invariation state. In the high inversion voltage region, the tunneling current plays a dominant role.

The plot of ln(J) against V, is shown (in Fig.7), which indicates that the current at low voltage (V < 0.3 V) varies exponentially with voltage. The characteristics can be described by

the standard diode equation: 0( 1) *qV nk TB J Je* where q is the electronic charge, V is the applied voltage, kB is the Boltzmann constant, n is the ideality factor and J0 is the saturation current density. Calculation of J0 and n from is obtained the measurements (in Fig.7). The value of the ideality factor of the violet SINP device is determined from the slop of the straight line region of the forward bias log(I)-V characteristics. At low forward bias (V< 0.2 V), the typical values of the ideality factors and the reverse saturation current density are 1.84 and 5.58×10-6A/cm2, respectively.

Using the standard diode equation 0( 1) *qV nk TB J Je* , where n = 1.84 and J0 = 5.58×10-6 A/cm2. The result of calculation is similar to that of the measurement (in I-V curve). By the same calculation method, the ideality factor and the reverse saturation current density of deep junction SINP photovoltaic device are 2.21 and 4.2 × 10-6 A/cm2, respectively. This result indicates that the recombination current *Jr* ≈ exp(*qV*/2*kT*) dominates in the forward current. The rectifying behaviors and the composition of dark current for violet SINP photovoltaic device is better than deep junction SINP device, because the ideality factor of the violet SINP

TCO-Si Based Heterojunction Photovoltaic Devices 131

quantum efficiency (IQE) or external quantum efficiency (EQE) for the evaluation of the spectra response of the light (Fig.8 and Fig.9). The photocurrent density (~ 3.08 × 10-3 A/cm2) of violet and blue enhanced SINP photovoltaic device is much higher than that of

The comparison of IQE, EQE and the responsivity for the violet and blue SINP photovoltaic device and the deep junction SINP photovoltaic device has been illustrated (in Fig.10 ~ Fig.12). In visible light region, the internal and external quantum efficiencies (IQE and EQE) of the devices are in the range of 75% to 85%. In the violet and blue region, the IQE and EQE of shallow junction violet SINP device is much higher than that of the deep junction SINP device. For example, the EQE and the responsivity of the violet SINP device are 70% and 285mA/W at 500nm, respectively, while the EQE and the responsivity of the deep junction SINP device are 42% and 167mA/W at 500nm, respectively. The spectral responsivity peak of violet and blue SINP photovoltaic device is 487mA/W at about 800nm. While the spectral responsivity peak of deep junction SINP photovoltaic device is 471mA/W at about 860nm. The high quantum efficiency and the responsivity of violet and blue enhanced photovoltaic cell attribute to the shallow junction and the good conductive, and the violet and blue

400 500 600 700 800 900 1000 1100

wavelength(nm)

Fig. 10. Comparison of IQE for violet and blue SINP photovoltaic device and the deep

<sup>90</sup> deep junction SINP photovolatic device

violet and blue enhanced SINP photovolatic device

deep junction SINP device (~ 2.23 × 10-3A/cm2), at V = 0.

**8.3.3 Spectral response and responsivity** 

Internal quantum efficiency(%)

junction SINP photovoltaic device.

antireflection of ITO film.

Fig. 8. I-V characteristic of the violet and blue enhanced SINP photovoltaic devices in dark and light (6.3 mW/cm2 - white light), respectively.

Fig. 9. I-V characteristic of the deep junction SINP devices in dark and light (6.3 mW/cm2 white light), respectively.

photovoltaic device (n=1.84) is lower than that of the deep junction SINP device (n=2.21). Furthermore, the values of IF/IR (IF and IR stand for forward and reverse current, respectively) at 1V for violet SINP device and deep junction SINP device are found to be as high as 324.7 and 98.4, respectively.

The weak light-injection I-V characteristics of the novel SINP devices with low power white light (6.3mW/cm2) illuminating were measured at 23C. It is observed that the novel SINP device exhibits a good photovoltaic effect and rectifying behavior in the photon – induced carrieres transportation. On the other side, another essential physical parameter is internal

)

current density(A/cm2

 dark light

and light (6.3 mW/cm2 - white light), respectively.

white light), respectively.

high as 324.7 and 98.4, respectively.


Fig. 8. I-V characteristic of the violet and blue enhanced SINP photovoltaic devices in dark


Fig. 9. I-V characteristic of the deep junction SINP devices in dark and light (6.3 mW/cm2 -

photovoltaic device (n=1.84) is lower than that of the deep junction SINP device (n=2.21). Furthermore, the values of IF/IR (IF and IR stand for forward and reverse current, respectively) at 1V for violet SINP device and deep junction SINP device are found to be as

The weak light-injection I-V characteristics of the novel SINP devices with low power white light (6.3mW/cm2) illuminating were measured at 23C. It is observed that the novel SINP device exhibits a good photovoltaic effect and rectifying behavior in the photon – induced carrieres transportation. On the other side, another essential physical parameter is internal


0.000

0.002

0.004

0.006

0.008

0.010

current density(A/cm2

 dark light

)

0.012

0.014


Voltage(V)

Voltage(V)

0.000

0.005

0.010

0.015

0.020

0.025

0.030

quantum efficiency (IQE) or external quantum efficiency (EQE) for the evaluation of the spectra response of the light (Fig.8 and Fig.9). The photocurrent density (~ 3.08 × 10-3 A/cm2) of violet and blue enhanced SINP photovoltaic device is much higher than that of deep junction SINP device (~ 2.23 × 10-3A/cm2), at V = 0.

#### **8.3.3 Spectral response and responsivity**

The comparison of IQE, EQE and the responsivity for the violet and blue SINP photovoltaic device and the deep junction SINP photovoltaic device has been illustrated (in Fig.10 ~ Fig.12). In visible light region, the internal and external quantum efficiencies (IQE and EQE) of the devices are in the range of 75% to 85%. In the violet and blue region, the IQE and EQE of shallow junction violet SINP device is much higher than that of the deep junction SINP device. For example, the EQE and the responsivity of the violet SINP device are 70% and 285mA/W at 500nm, respectively, while the EQE and the responsivity of the deep junction SINP device are 42% and 167mA/W at 500nm, respectively. The spectral responsivity peak of violet and blue SINP photovoltaic device is 487mA/W at about 800nm. While the spectral responsivity peak of deep junction SINP photovoltaic device is 471mA/W at about 860nm. The high quantum efficiency and the responsivity of violet and blue enhanced photovoltaic cell attribute to the shallow junction and the good conductive, and the violet and blue antireflection of ITO film.

Fig. 10. Comparison of IQE for violet and blue SINP photovoltaic device and the deep junction SINP photovoltaic device.

TCO-Si Based Heterojunction Photovoltaic Devices 133

rectifying and obvious photovoltaic behaviors are obtained and analyzed by I-V measurements. The spectral response and the responsivity with a higher quantum efficiency of the violet SINP photovoltaic device and the deep junction SINP photovoltaic device were analyzed in detail. The results indicated that the novel violet and blue enhanced photovoltaic device could be not only used for high quantum efficiency of violet and blue enhanced silicon photodetector for various applications, but also could be used for the high

**9. Fabrication and photoelectric properties of AZO/SiO2/p-Si heterojunction** 

As shown in the previous work, semiconductor-insulator-semiconductor (SIS) diodes have certain features, which make them more attractive for the solar energy conversion than conventional Shottky, MIS, or other heterojunction structures (Mridha et al., 2007). For example, efficient SIS solar cells such as indium tin oxide (ITO) on silicon have been reported, where the crystal structures and the lattice parameters of Si (diamond, a = 0.5431 nm), SnO2 (tetragonal, a = 0.4737 nm, c = 0.3185 nm), In2O3 (cubic, a = 1.0118 nm) show that they are not particularly compatible and thus not likely to form good devices. However, the SIS structure is potentially more stable and theoretically more efficient than either a Schottky or a MIS structure. The origins of this potential superiority are the suppression of majority-carrier tunneling in the high potential barrier region of SIS structure, and the existence of thin interface layer which minimizes the amount and the impact of the interface states. This results in an extensive choice of the p-n junction partner with a matching band gap in the front layer. In addition, the top semiconductor film can serve as an antireflection coating (Dengyuan et al., 2002), a low-resistance window, and the collector of the p-n

Furthermore, the semiconductor with a wide band gap as the top layer of SIS structure can eliminate the surface dead layer which often occurs within the homojunction devices, such as the normal bulk silicon based solar cells. On the other side, this absence of the light absorption of visible region in a surface layer can improve the ultraviolet response of the internal quantum efficiency. Among many transparent conductive oxides (TCO) of the transition metals, ZnO:Al is one the best n-type semiconductor layer. It has high conductivity, high transmittance, optimized surface texture for light trapping, and large band gap of Eg≈ 3.3 eV. Thus, in this description, we show a photovoltaic device with AZO/SiO2/p-Si frame, as an attempt to study its opto-electronic conversion property and the I-V features as well. The schematic and the bandgap structure of the novel

For the purpose of fabricating SIS structure, p-type Si (100) wafers were used as the substrates of the heterojunction device. The wafers were firstly prepared by a stand cleaning procedure, then, they were dipped in 10% HF solution for one minute to remove native

By thermal evaporation, 1 μm-thick Al electrode was deposited on the back side. Then the samples were annealed at 500°C for 20 min in N2:O2=4:1 condition to form good ohmic

contact and a very thin oxide layer (about 15~20Å) was grown on the p-Si surface.

AZO/SiO2/p-Si SIS heterojunction device was show here (Fig.13).

oxide layer. Finally, the wafers were dried in a flow gas of nitrogen.

efficiency solar cell.

**9.1 Introduction** 

junction as well.

**9.2 Experimental in details** 

**device** 

Fig. 11. Comparison of EQE for violet and the blue SINP photovoltaic device and the deep junction SINP photovoltaic device.

Fig. 12. Comparison of the responsivity for the violet and blue SINP photovoltaic device and the deep junction SINP photovoltaic device.

#### **8.3.4 Conclusions**

The novel ITO/SiO2/np Silicon SINP violet and blue enhanced photovoltaic device has been fabricated by thermal diffusion of phosphorus for shallow junction to enhance the spectral responsivity within the wavelength range of 400-600nm, the low temperature thermally grown a very thin silicon dioxide and RF sputtering ITO antireflection coating to reduce the reflected light and enhance the sensitivity. The ITO film was evinced to a high quality by UV-VIS spectrophotometer, four point probe and Hall-effect measurement. Fairly good

rectifying and obvious photovoltaic behaviors are obtained and analyzed by I-V measurements. The spectral response and the responsivity with a higher quantum efficiency of the violet SINP photovoltaic device and the deep junction SINP photovoltaic device were analyzed in detail. The results indicated that the novel violet and blue enhanced photovoltaic device could be not only used for high quantum efficiency of violet and blue enhanced silicon photodetector for various applications, but also could be used for the high efficiency solar cell.
