High resistivity In-doped ZnTe: electrical and optical properties

Abstract

Semi-insulating <111> ZnTe prepared by In doping during Bridgman growth was found to have a resistivity of 5⋅ ⋅74 × 10 7 ohm-cm, the highest reported so far in ZnTe, with hole concentration of 2⋅ ⋅4 × 10 9 /cm 3 and hole mobility of 46 cm 2 /V⋅ ⋅s at 300 K. The optical band gap was 2⋅ ⋅06 eV at 293 K compared with 2⋅ ⋅26 eV for undoped semiconducting ZnTe. Thermally stimulated current (TSC) studies revealed 2 trap levels at depths of 202-222 meV and 412-419 meV, respectively. Photoluminescence (PL) studies at 10 K showed strong peaks at 1⋅ ⋅37 eV and 1⋅ ⋅03 eV with a weak shoulder at 1⋅ ⋅43 eV. Short anneal for 3 min at 250°C led to conversion to a p-type material with resistivity, 14⋅ ⋅5 ohm-cm, indicating metastable behaviour. Raman studies carried out on undoped and In-doped samples showed small but significant differences. Possible models for semi-insulating behaviour and meta-stability are proposed.

Injection and Optical Spectroscopy of Localized States in II-VI Semiconductor Films

“…Authors [13,92] explain the peak Ei= 1.538 eV as one of unknown nature. Similar interpretation is also in [89] where the line Ei= 1.539 eV is caused by DAP (here the acceptor is sodium, Cd Na ). The next peak Ei = 1.525 eV is likely is the phonon repetition of the previous one ( -A)-LO [96].…”

“…A modest energetical displacement of lines in spectra from epitaxial films comparing to those from the polycrystalline layers films deposited on glass may be caused by presence of sufficient macrodeformations in the layers CdTe/BaF2. PL spectra from CdTe layers have lines originated from optical transfers with participation of free and bound excitons, transfers valence band -acceptor ( -А), donor-acceptor transfers (DAP), the radiation caused by presence of dislocations or DP (donor pairs, DP) (Y -stripes); the spectra also have a set of lines corresponding to optical transitions where phonons take place (LO -phonon replica) [87][88][89][90][91][92][93][94][95][96][97][98][99]. Activation energies relative to the valence band (while the most samples were of p-type conductivity) were calculated using expression (26) (in analogy with description above).…”

“…Table 7. Analysis and interpretation of the PL peaks are carried out according to reference data [75][76][77][78][79][80][81][82][83][84][85][86][87][88][89]. We calculated activation energies of corresponding processes using the expression (26).…”

Investigation of electrical properties of $$\hbox {In/ZnIn}_{2} \hbox {Te}_{4}/\hbox {n-Si/Ag}~\hbox {diode}$$ In/ZnIn 2 Te 4 / n-Si/Ag

“…In photovoltaic applications, to obtain higher efficiency, ZnTe thin film buffer layers are used in CdTe-based diodes [7] and since it is a wide band gap material, it can be used as a window film layer in tandem solar cells [2]. On the other hand, due to high resistive behaviour, in recent years, the dopants from group-I (Ag, Cu) and group-III (Al, Ga and In) have been used to tune its electronic properties [8][9][10]. In this case, there are several studies on its ternary analogous as ZnIn 2 Te 4 (ZIT) introducing In to this binary compound of ZnTe [11][12][13][14][15][16][17].…”

Theoretical investigation of optical properties and band gap engineering for Zn 1−x TM x Te ( TM = Fe, Co) alloys by modified Becke–Johnson potential

“…[1] It has been reported that Cr-doped ZnTe reveals maximum absorption in the UV energy range and the band gap decreases compared with the undoped ZnTe. [15,16] T M-doped ZnTe also finds applications as the back contact for cadmium based solar cells. The Cu-, Mo-, and V-doped ZnTe materials are used for back contact materials but they have a few limitations.…”