Nature of AX Centers in Antimony-Doped Cadmium Telluride Nanobelts

Abstract

Single crystalline p-type CdTe:Sb nanobelts were fabricated using an Au-catalyzed chemical vapor deposition method. Low carrier concentration and low mobility even at high Sb incorporation manifest compensation in the system. From cross examination of temperature-dependent charge transport and photoluminescence measurements, two major acceptor levels induced by Sb doping are determined: a shallow level attributed to substitutional Sb dopants without lattice relaxation and an associated deeper level resulted from large lattice relaxation-AX centers. Persistent photoconductivity and hysteresis photoconductance under the thermal cycle elucidate the nature of AX centers. This comprehensive investigation of the impurity levels in the material system is essential for the design and development of nanoelectronic devices based on the CdTe nanostructures.

Synthesis, Characterizations and Applications of Cadmium Chalcogenide Nanowires: A Review

“…From cross examination of temperature-dependent charge transport and photoluminescence measurements, two major acceptor levels induced by Sb doping are determined: a shallow level attributed to substitutional Sb dopants without lattice relaxation and an associated deeper level resulted from large lattice relaxation, so called AX centers. Persistent photoconductivity and hysteresis photoconductance under thermal cycle verify the existence of AX centers [137] .…”

“…This attributes to the self-compensation of acceptor impurities. Huang et al have recently investigated the nature of Sb dopants in CdTe nanowires, and have found surprisingly that in addition to shallow acceptor state, Sb induces deep level AX centers, resulting in significant compensations, manifested by the low carrier concentration and low mobility even at high Sb incorporation [137] . From cross examination of temperature-dependent charge transport and photoluminescence measurements, two major acceptor levels induced by Sb doping are determined: a shallow level attributed to substitutional Sb dopants without lattice relaxation and an associated deeper level resulted from large lattice relaxation, so called AX centers.…”

Improving gas sensing by CdTe decoration of individual Aerographite microtubes

“…However, it is most likely caused by AG microtubes [23,24], as the MonoCL image in figure 2(c) reveals good coincidence of luminescence and SEM image. The luminescence at ∼770 nm can be clearly attributed to near band edge luminescence of the CdTe layer originating either from band-to-band or even excitonic recombination [25][26][27]. Furthermore, the luminescence at ∼850 nm in CdTe is caused by donor-acceptor-pair and free-to-bound transitions/recombinations (most likely of an electron with acceptor bound hole-[e, A], as as-grown CdTe is typically a p-type material).…”

Quantifying Large Lattice Relaxations in Photovoltaic Devices

“…Hence, the single defect level picture is insufficient and defect transformations can result in unique, time-dependent electronic properties. Some examples include persistent photoconductivity (PPC) in III-V materials (such as, AlGaAs, caused by DX and EL2 center defects [2,3]), PPC in II-VI materials (such as, CdS [4,5] and CdTe [6]), photo-degradation of hydrogenated amorphous silicon (a-Si:H) caused by dangling bond defects [7], charge-induced free carrier lifetime decay in crystalline silicon due to metastable boron-oxygen complexes [8], and impediments to doping of CdTe due to self-compensation by AX centers [9,10]. Fundamental understanding of materials with LLR defects can improve the performance and reliability of semiconductor devices.…”