**5. Summary**

The last two decades have indisputably witnessed incredible advances in the MBE growth of III-Nitrides and their applications in the area of photodetection. In this chapter, the important concepts about PDs, including the fundamental evaluation parameters and the various sensing mechanisms have been discussed. These mechanisms usually depend on the type of the photoactive material used to fabricate the device. Next, the basic properties of III-Nitrides and the common synthesis techniques used for their production have been reviewed briefly. Finally, a progressive discussion about the PDs based on the III-Nitrides fabricated through MBE has been given and summarized in **Table 1**. These extensive achievements have indisputably established MBE as one of the most reliable methods for fabricating high-quality III-Nitrides and these devices certainly have a lot of potential for the development of the advanced III-Nitrides-based PDs in future.


**167**

**6. Outlook**

**Table 1.**

have been summarized below:

*Group III-Nitrides and Their Hybrid Structures for Next-Generation Photodetectors*

**(mAW−1)**

(18 μW/cm2

(0.06 mW/cm2

(13 mW)

@ 1550 nm (106.2 mW/cm2

(0.3 mW/cm2

(0.14 mW/cm2

p-GaN/n-ZnMgO [24] 0 196 @ 362 nm — 1.7/3.3

 @ 365 nm (0.3 mW/cm2

 @ 365 nm (12 mW/cm2

)

)

)

)

)

)

)

)

)

 @ 580 nm (0.1 mW/cm2

 @ 900 nm (0.05 mW/cm2

**Detectivity (Jones)**

**Rise/Fall Times (ms)**

> / 7.65⨯104

— 1.12⨯104

~1011 5.3/5.6

1.45⨯1010 60/267

3⨯1013 50/120

2.4⨯1010 63/27

— 10/18

— 20/33

2.62⨯1011 680/700

1.93⨯1013 19.9⨯10−3/

9.39⨯1012 12.5⨯10−3/

21.4⨯10−3

14.9⨯10−3

Based upon the analysis of the reported devices in this field, a perspective regarding the future of III-Nitrides-based devices and the related follow-up work

• The use of transition metal dichalcogenides (TMDCs) as substrates for epitaxial growth of III-Nitrides has been unexplored. TMDCs have a very small lattice mismatch with the III-Nitrides [67], and therefore, high-quality growth

• The use of 2D transparent materials like graphene, graphene derivatives and 1T phase of TMDCs (semi-metallic), can be used as contact electrodes instead of the conventional metals, as the area for the light absorption gets maximized along with the outstanding electronic properties of these 2D semiconductors.

• Another interesting possibility would be combining non-polar nitrides with layered materials. The absence of the internal polarization field would provide a band to band transition, which is usually absent in the polar devices because of the quantum confined Stark effect at the interfaces. This property is very important for effective photodetection and has been evident from some of the very early works reported on the nonpolar *a*-GaN. Additionally, the presence of anisotropy in electrical conductivity as well as mobility can be helpful in

tuning the optoelectronic and electronic properties of the PD.

can be expected which would result into better device performance.

*DOI: http://dx.doi.org/10.5772/intechopen.95389*

**PD Bias (V) Responsivity** 

rGO/GaN [62] 0 1.54 @ 350 nm

*a*-GaN [63] 0 4.67 @ 364 nm

GaN Nanoflowers [64] 0 132 @ 325 nm

InN/AlN/Si [25] 0 3.36⨯10−3

n-InGaN/n-Si [65] 0 94.2 @ 310–380 nm

GaN/rGO: Ag NP [66] 0 266 @ 360 nm

*Comparison of the device performance parameters of various PDs discussed.*

InGaN/AlN/Si [15] 0 9.64⨯103

MoS2/AlN/Si [4] 0 10⨯103

ZnO/AlN/Si [13] −4 1.45⨯104

MoS2/GaN [20] 1 3⨯106


*Group III-Nitrides and Their Hybrid Structures for Next-Generation Photodetectors DOI: http://dx.doi.org/10.5772/intechopen.95389*

#### **Table 1.**

*Light-Emitting Diodes and Photodetectors - Advances and Future Directions*

device performance (**Figure 10(b)**).

**5. Summary**

In a recent work, Singh et al*.* [4] have fabricated an MoS2/AlN/Si-based PD, combining the mature technologies of III-Nitride and Si with the unique properties of MoS2. Additionally, due to the large difference between the work functions of these semiconducting materials, the band bending at the heterointerfaces resulted into the self-driven behavior. The vertical transport behavior of the device shows a broad-band photoresponse (300–1100 nm) with maximum responsivity of ~10 AW−1 under self-biased condition as shown in **Figure 10(a)**. The device also shows an ultrafast detection speeds (response/recovery times: ~13/15 μs). The importance of sandwiching the AlN layer has been shown as the MoS2/Si-based PD shows a responsivity ~5 times less in the zero-bias mode. The authors have confirmed through transmission electron microscopy and X-ray photoelectron spectroscopy that oxygen defects exist throughout the AlN layer. These impurities form deep donor levels in AlN and moderate the charge transport, which leads to the enhanced

The last two decades have indisputably witnessed incredible advances in the MBE growth of III-Nitrides and their applications in the area of photodetection. In this chapter, the important concepts about PDs, including the fundamental evaluation parameters and the various sensing mechanisms have been discussed. These mechanisms usually depend on the type of the photoactive material used to fabricate the device. Next, the basic properties of III-Nitrides and the common synthesis techniques used for their production have been reviewed briefly. Finally, a progressive discussion about the PDs based on the III-Nitrides fabricated through MBE has been given and summarized in **Table 1**. These extensive achievements have indisputably established MBE as one of the most reliable methods for fabricating high-quality III-Nitrides and these devices certainly have a lot of potential for

**(mAW−1)**

(4 mW)

(13 mW)

(0.3 mW/cm2

(0.8 W/m2 ) )

)

)

 @ 360 nm (0.3 mW/cm2

 @ 360 nm (0.3 mW/cm2

> @ 350 nm (413 K)

InN QDs [49] 3 — — 1.43⨯103

**Detectivity (Jones)**

@ 366 nm — —

@ 300 nm — —

— —

— —

— 6⨯103

— 210/

— 222/

— —

2.57⨯1012 320/220

**Rise/Fall Times (ms)**

> / 1.22⨯103

> > / 15⨯103

1.2⨯103

2.1⨯103

the development of the advanced III-Nitrides-based PDs in future.

**PD Bias (V) Responsivity** 

Ag-GaN-Pt [47] 5 633 @ 325 nm

GaN NS/Si [48] 1 5.7 @ 325 nm

*a*-GaN [50] 2 155 @ 360 nm

*a*-GaN [18] 1 1.9⨯103

*a*-GaN [51] 1 2.5⨯104

GaN [52] 1 4.6⨯106

GaN/AlN QDs [54] -1 2⨯106

BTO/GaN [21] 5 4.5⨯104

GaN [53] 15 183 @ 362 nm

**166**

*Comparison of the device performance parameters of various PDs discussed.*
