Au Film Electrodes on CdZn Te Surface: Preparation and Ohmic Contact Property

doi:10.15541/jim20170186

Abstract

Abstract:

Tellurium cadmium zinc (CdZnTe) is a kind of II - VI wide band-gap semiconductor compound, which is a promising material to fabricate the X- or γ-ray detectors. Its Ohmic contact property significantly influences the detector performance. In order to study the influence of preparation technology on Ohmic contact properties of the electrode, Au film electrodes were deposited by sputtering deposition, vacuum evaporation and electroless deposition. By analyzing I-V curves, SEM and AC impedance spectra, microstructure and Ohmic contact properties of the samples were studied. The results show that surtace of the sample prepared by the electroless deposition is smooth and dense showing lower contact barrier and better Ohmic contact properties smooth and Ohmic contact properties of the electrodes. After annealing at 100℃, the Ohmic coefficient of the Au electrode prepared by electroless deposition increases from 0.883 to 0.915, and the barrier height reduces from 0.492 eV to 0.487 eV, displaying improved. AC impedance spectroscopy shows that it is the change of impurity-doping and defects of CdZnTe surface at the interface that attribute to the lowest contact barrier of the Au electrode prepared by electroless deposition.

Key words: CdZnTe, Au film preparation, Ohmic contact, AC impedance spectra

CLC Number:

O472

XIE Jing-Hui, LIU Yu-Cong, WANG Chao, YIN Zi-Wei, CHEN Jia-Dong, DENG Hui-Yong, SHEN Yue, WANG Lin-Jun, ZHANG Jian-Guo, DAI Ning. Au Film Electrodes on CdZn Te Surface: Preparation and Ohmic Contact Property[J]. Journal of Inorganic Materials, 2018, 33(3): 273-278.

Figures/Tables 6

Fig. 1 SEM images of Au film electrode prepared under different preparation conditions(a) Sputtering method; (b) Vacuum evaporation method; (c) Electroless deposition method; (d) Annealing after sputtering; (e) Annealing after vacuum evaporation; (f) Annealing after electroless deposition

Fig. 2 I-V curves of the samples before (a) and after annealing at 100℃ for 2 h in air (b)

Table 1 Change of the Ohm coefficient for different samples

	Sp	Ev	Ele
b(before annealing)	1.346	0.771	0.883
b(annealing for 2 h)	1.213	0.875	0.915

Fig. 3 lg J-V curves of the samples before (a) and after annealing at 100℃ for 2 h (b)

Table 2 Change of the barrier height for different samples

	Sp	Ev	Ele
${{\varphi }_{\text{B}}}$/eV(before annealing)	0.503	0.498	0.492
${{\varphi }_{\text{B}}}$/eV(annealing for 2 h)	0.494	0.493	0.487

Fig. 4 Dependence of the imaginary part of impedance on the frequency

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