Investigation of excess 1/fnoise in CdTe single crystals

Abstract

Experimental studies of noise characteristics of CdTe crystals, prepared using the travelling heater method, have been carried out. Three types of basic material were used: low-ohmic n-type with n = 5 × 10 15 cm −3 , semi-insulating n-type with n = 1.5 × 10 9 cm −3 and low-ohmic p-type with holes concentration p = 7 × 10 14 cm −3 . The noise measurements show that the dominant noise is 1/f n noise with parameter n in range from 0.9 to 1.5 and often very close to 1. The experimental value of 1/f noise is always much higher than the theoretical value which corresponds to the total value of free carriers in the sample. The voltage noise spectral density of 1/f noise depends on the quantity of free carriers in the sample. Free carriers are distributed uniformly throughout the homogenous part of the sample. But within the depleted region there is very low concentration of free carriers which increases exponentially in the direction from the contact area to the homogenous part of the sample. Analysis shows that the excess 1/f noise is caused by the low carrier concentration within the depleted region at the metal-semiconductor junction.

Aligned networks of cadmium sulfidenanowires for highly flexible photodetectors with improved photoconductive responses

“…[51][52][53] The noise from point defects in single crystalline channels was usually reported to exhibit 1/f behavior. [54][55][56] On the other hand, in polycrystalline channels comprised of multiple grains, the barrier heights on the grain boundaries can fluctuate and generate the noise with 1/f 2 behavior. 51,52,57 In our case, we observed 1/f noise behavior in our devices, indicating that the dominant noise source is point defects rather than grain boundaries.…”

Symmetrical current–voltage characteristic of a metal–semiconductor–metal structure of Schottky contacts and parameter retrieval of a CdTe structure

“…Two identical golden contacts were fabricated on the studied sample. The contacts are Schottky type where the work function of gold, φ M = 5.37 eV, is smaller than that for the p-type sample, φ S = 5.75 eV, [18]. The sample dimensions are 1.7 × 2.7 × 11.4 mm 3 .…”

Ageing of Cadmium Telluride Radiation Detectors and its Diagnostics with Low Frequency Noise

“…Similar processes are in p-type samples. For the studied CdTe detectors ф M > ф S for an n-type CdTe and ф M < ф S for a p-type CdTe, this leads to appearance of rectifying contacts at the metalsemiconductor junction [14]. All the studied detectors with p-type and n-type semiconductors have two rectifying contacts.…”