Identification of theBiGaheteroantisite defect in GaAs:Bi

Abstract

GaAs lightly doped with the heaviest group-V atom, bismuth (Bi), has been studied by conventional electron-spin resonance (ESR) and by ESR detected via the magnetic-circular-dichroism (MCD) absorption. A new Bi-related sharp-line MCD band has been observed on which two MCD-ESR lines have been discovered. They are shown to arise from the singly ionized Biz, double donor. Most remarkably, a substantial fraction, about 10%, of the total Bi content is found to occupy the Ga site. The BiG, MCD absorption band is tentatively assigned to an exciton deeply bound to the singly ionized double donor + Bi~,

Direct Evidence for As as a Zn-Site Impurity in ZnO

“…The site change to T sites (1.6 Å from S Zn ) observed for part of the probe atoms following 900 C vacuum annealing indicates that O-poor annealing conditions could alter the nature of the complexes. While many examples of minority antisite defects in semiconductors have already been reported, e.g., As Ga [1] or Bi Ga [7] in GaAs, the case of As in ZnO is different since it concerns an impurity where even the most common lattice site is contrary to what one would simply expect from its position in the periodic system. The Zn-site character of As can be explained from the large size mismatch of As 3ÿ with O 2ÿ but the good match between As 3 and Zn 2 (0.58 Å vs 0.60 Å ), its electronegativity of 2.0, which is closer to Zn (1.6) than to O (3.5), and its character as a semimetal, all of which make it energetically favorable for the As impurity to be incorporated on Zn sites [19,20].…”

“…However, while Si, Ge, Sn, and Pb mainly replace Ga and are therefore more commonly found as donors, C preferentially replaces As and the acceptor state dominates [4 -6]. On the other hand, it has been estimated that around 10% of Bi impurities occupy Ga sites in GaAs, acting as double donors [7] and thus illustrating the competing characteristics of Bi as a metal and a group V element. As was pointed out by Desnica [8] and is illustrated in this Letter, size matching between the atomic radii of impurities and host atoms acts as an additional important criterion determining the lattice sites of foreign atoms in semiconductors and hence must be taken into account when assessing the nature of their role as acceptors or donors.…”

Novel Dilute Bismide, Epitaxy, Physical Properties and Device Application

“…Bismuth is widely believed to substitute group-V in the matrix. However, Kunzer et al confirmed that about 10 % of the incorporated Bi had occupied the Ga sites in GaAsBi films [207]. 7.024 Å [26] 6.1.3.…”

Identification of an isolated arsenic antisite defect in GaAsBi

“…Indeed, recent DLTS measurements [23][24][25] have revealed the presence of a number of carrier traps in GaAsBi alloys. Bi Ga antisite defects were also reported 26 in GaAs lightly doped with Bi. An improved understanding of the microscopic structure of major grown-in defects and impurities along with their influence on physical properties of the GaAsBi alloy is critically needed in order to control them and to fully explore the potential of dilute bismides for device applications.…”

“…[34][35][36][37][38][39][40][41][42][43] As the linewidth is determined by the hyperfine interaction with the ligand atoms surrounding the As Ga , this finding is thereby indicative of identical local surrounding of As Ga in both GaAs and GaAsBi, i.e., Bi is not one of the nearest neighbors of the As Ga in GaAsBi studied here. Previous ESR studies 26 of Czochralski-grown GaAs lightly doped with Bi revealed that a substantial fraction (about 10%) of Bi dopants occupied the Ga site, forming Bi Ga antisite defects. Despite considerable efforts, however, we found no experimental evidence for such behavior in the studied GaAsBi alloys.…”