Low Frequency Noise of the CdTe Crystals

conference paper

English

Experimental studies of transport and noise characteristics of CdTe bulk single crystals have been carried out. The noise measurement was used to characterized the quality of sample surface and contact technology. As a quality indicator we have choose the 1/f noise. In this case the 1/f noise is generated in sample volume, on surface and contacts. The main problem to be solved was the separation of these noise sources. The noise spectral density was measured by four probe method to separate contact noise from the other sources. To distinguish between 1/f noise generated in sample volume and on the surface the noise measurement was performed as a function of incident light wavelengths for constant electric field and current was varied both by the sample illumination and photon energy change. There are three different 1/f noise sources: bulk 1/f noise generated by sub band gap energy photons with current noise spectral density proportional to first power of current, surface 1/f noise generated by over band gap energy photons with current noise spectral density proportional to second power of current, contact 1/f noise with current noise spectral density proportional to higher than second power of current. Experimental results are used to distinguish between McWhorter model in which 1/f type noise is a result of mobile carrier number fluctuations and Hooge model, which explains 1/f noise as mobility fluctuations. The additivity of GR spectra proposed by McWhorter is a serious problem. There is experimental proof that in high-quality samples with low surface recombination the 1/f noise is a fluctuation in the mobility.

CdTe crystal, low frequency noise

GRMELA, L.; ŠIKULA, J.; ZAJAČEK, J.; MORAVEC, P.

2005

19. 9. 2005

American Institute of Physics

Melville, USA

0-7354-0267-1

Noise and Fluctuations

175

178

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