**Part 2**

**Bolometer Types and Properties** 

50 Bolometers

Sedky, S.; Fiorini, P.; Caymax, M.; Baert, C.; Hermans L.; Mertens, R. (1998).

Takami, H.; Kawatani, K.; Kanki, T.; Tanaka, H. (2011). High Temperature-Coefficient of

Torres, A.; Moreno, M.; Kosarev, A.; Heredia, A. (2008). Thermo-sensing Germanium-Boron-

*Crystalline Solids*, Vol. 354, pp. 2556-2560, ISSN 0022-3093.

No. 4, pp. 503-510. ISSN 1057-7157.

055804-1 - 055804-3, ISSN 0021-4922.

ISSN 0018-9383.

CMOS Integrated Sensor Array, *Journal of Microelectromechanical systems*, Vol. 10,

Characterization of Bolometers Based on Polycrystalline Silicon Germanium Alloys, *IEEE Electron Device Letters*, Vol. 19, No. 10, pp. 376- 378. ISSN 0741-3106. Tanaka, A.; Matsumoto, S.; Tsukamoto, N.; Itoh, S.; Chiba, K.; Endoh, T.; Nakazato, A.;

Okuyama, K.; Kumazawa, Y.; Hijikawa, M.; Gotoh, H.; Tanaka, T.; Teranishi, N. (1996). Infrared focal plane array incorporating silicon IC process compatible bolometer, *IEEE Transactions on Electron Devices*, Vol. 43, Issue 11, pp. 1844 – 1850,

Resistance at Room Temperature in W-Doped VO2 Thin Films on Al2O3 Substrate and Their Thickness Dependence, *Japanese Journal of Applied Physics,* Vol. 50, pp.

Silicon Films Prepared by Plasma for Un-cooled Micro-bolometers, *Journal of Non* 

**3** 

Béla Szentpáli

*Hungary*

**Noise Limitations of Miniature** 

**Thermistors and Bolometers** 

*Hungarian Academy of Sciences, Research Institute for* 

*E kCT* , (1)

(2)

, (3)

 

The miniature thermal resistors are comprehensively applied as thermistors or bolometers. Due to the dynamic development of the micromachining technologies became possible their mass-production with the precision and reproducibility of the microelectronics. These techniques result in typical lateral dimensions in the 1….100 µm range and thicknesses about µm, or less. The miniature devices fulfil the present-day requirements of the measuring and regulating systems demanding a large number of high-speed sensors for following quick changes, or for ensuring the quick read-out in integrated systems comprising many devices. However the higher working speed demands electronic processing circuits with broader bandwidth and consequently higher noise. Therefore it

The phenomenological thermodynamic parameters depend on the average of the chaotic motion of the atoms and/or molecules. Therefore some fluctuations of their values are expected especially in very small volumes. This fact sets a physical limitation to the miniaturization; the size of the device should be large enough for representing the thermal parameters with the desired accuracy. According to the statistical physics (see eg. Kingston

2 2

where k, C and T are the Boltzmann constant, the heat capacitance of the volume under discussion and the absolute temperature respectively. Because ܧ ൌ ܥܶ,) 1 (can be rearranged:

> *Tk T k T CT C*

This criterion stands a lower limit to the dimensions of the miniature thermal sensors, but it is in the nanometre region. For example in 1 µm3 platinum δT/T = 1,6\*10-6 and similarly in 1 µm3 Si δT/T = 2\*10-6. It depends on the application whether it is a practical limitation or not.

> *rT r T T r T* ( ) (1 ( )) (1 ) *m mm*

 

2 2

The temperature changes of the thermistor lead to changes of the resistance, as

seems worth to reconsider the electronic noises of the miniature devices.

1978) the mean square fluctuations of the energy is

**1. Introduction** 

*Technical Physics and Materials Science,* 
