Identification of deep centers in ZnSe

Abstract

Cu-doped, Mn-doped, and nominally undoped ZnSe crystals were prepared by vapor transport or sublimation. The presence of the dopants was established by photoluminescence EPR, atomic absorption, and radiotracer techniques, and their associated energy levels studied by photoluminescence. From measurements of photocurrent and photocapacitance, it was shown that Cu doping introduces an energy level at about 0.68 eV above the valence band. From the good agreement between the optical cross sections obtained from the measurement of photocapacitance and optical quenching of photoluminescence, it was concluded that this center is responsible for the red Cu-emission in photoluminescence. This conclusion was supported by the observation that the absolute concentration of this level agrees with the reduction of the free-carrier concentration caused by Cu doping. Owing, presumably, to residual copper contamination, the 0.68-eV center was sometimes detected in nonintentionally doped and Mn-doped material. Evidence is given that this center is identical to the M center reported previously in Mn-doped ZnSe is identical with the 0.68-eV energy level. Independent of dopant, another level at about 0.58 eV above the valence band was observed.

Fingerprinting Electronic Structure in Nanomaterials: A Methodology Illustrated by ZnSe Nanowires

“…For the red emission, it is well-documented that the acceptor level exists eV above the valence band edge. − From eV, the donor level is approximately 0.15 eV below the conduction band edge, which agrees well with Iida, Besomi, and Meneses who attributed the donor to a metal impurity, possibly indium. For the green emission, the acceptor level ,, is approximately eV above the valence band edge, giving a donor energy level 0.03 eV below the conduction band edge, which is within the error of the shallow donor value given by the hydrogen model, meV.…”

Luminescence study of ZnSe based scintillators in frequency domain

“…The defect-related emission of ZnSe scintillators consists of at least two spectral components [6,10,[13][14][15]. Luminescence mechanisms in this spectral region and relationship of the emission parameters with conditions of growth, annealing, and doping are extensively studied, but still not fully understood.…”

Dielectric Spectroscopy Study Of Znse Grown By Physical Vapor Transport

“…As grown ZnSe is not semiconducting, but rather is insulating due to self compensation [3][4][5][6]. One method for eliminating self-compensation is by annealing the crystal in molten zinc [3][4][5][6].…”

“…One method for eliminating self-compensation is by annealing the crystal in molten zinc [3][4][5][6]. This method was started by Aven in 1962 [7], and is the continued practice to this day.…”

“…This method was started by Aven in 1962 [7], and is the continued practice to this day. It is thought that it helps to purify the ZnSe and eliminate Zn vacancies that form upon crystallization [5,6]. Some researchers have found that excessive annealing will create the opposite effect and lead to impurities and decrease of mobility [6].…”