A thermodynamic equilibrium model for CdTe annealed under Te vapor is established, in which possible point defects and a defect reaction existing in undoped and In-doped Te-rich CdTe crystals are taken into consideration. Independent point defects, such as VCd, Cdi, and Tei, as well as defect complexes, namely TeCd-VCd (B complex), \( {\hbox{Te}}_{\rm{Cd}}^{2 + } \)-\( {\hbox{V}}_{\rm{Cd}}^{2 - } \) (D complex), \( {\hbox{In}}_{\rm{Cd}}^{ + } \)-\( {\hbox{V}}_{\rm{Cd}}^{ - } \) (A-center) and Tei-VCd (TeCd), are discussed based on the defect chemistry theory. More specially, the mass action law and quasi-chemical equations are used to calculate defects concentration and Fermi level in undoped and doped CdTe crystals with different indium concentrations. It is found that the Fermi level is controlled by a \( {\hbox{V}}_{\rm{Cd}}^{2 - } \), TeCd, and B/D-complex in undoped crystal. The concentration of VCd drops down in an obvious manner and that of TeCd rises for doped crystal with increasing [In].

研究了生长态CdZnTe晶体在经历了不同温度和时间的Cd/Zn和Te气氛退火后,其光电性能的变化规律.研究表明,在Cd/Zn气氛下退火180 h后,CdZnTe晶体中直径在5μm以上的Te夹杂的密度减小了1个数量级,晶体的体电阻率由1010 Ω·cm减小至～107 Ω· cm.同时发现,Cd/Zn源区的温度决定了退火后晶体在500～4000cm-1范围内红外透过率曲线的平直状态,这可能与晶体中的Cd间隙缺陷浓度相关,而与晶体中的载流子浓度和夹杂/沉淀相状态无关.在Te气氛下退火时,发现晶体的红外透过率的平直状态与晶体电阻率的对数lg(ρ)呈近似线性关系,同样可归因于退火过程中Cd间隙缺陷的浓度变化.

基于缺陷化学理论,考虑到富Te的CdTe晶体中可能存在的点缺陷,建立了在Te气氛下退火时,热力学平衡态晶体中的点缺陷模型,其中包括Cd间隙(Cdi)、Cd空位(VCd)、Te间隙(Tei)和Te反位(TeCd).利用质量作用定律和伪化学平衡方程计算了富Te情况下本征CdTe晶体中的点缺陷浓度和费米能级.计算结果系统的揭示了点缺陷浓度、费米能级、Te压以及退火温度之间的关系,发现只有TeCd浓度足够大时才能对费米能级产生钉扎作用.

The dislocation-mediated coupling mechanism between the microstructural defects and Te inclusions in CdZnTe crystal have been investigated through the defect-selective etching and cathodoluminescence (CL). The enrichment of well-arranged dislocation-related defects was found around the Te inclusions. A dislocation-mediated defects interaction model was proposed and native deep-level defects were considered to be associated with induced dislocation motions, showing as a dark CL contrast. The spatial arrangement of the microstructural defects were confined to a stellated octahedron. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The variation of density and diameter of Te inclusions in indium-doped Cd0.9 Zn0.1 Te (CZT)single crys-tals during annealing under Cd/Zn vapor were studied via IR microscopy observation.The results indicated that the density of Te inclusions distributed homogeneously before annealing,while after annealing,the density of Te inclusions increased for about one order near the surface,but decreased for one order inside,and the density increased gradually along the direction of temperature gradient.The diameter of Te inclusions was mainly be-tween 1 μm and 25 μm before annealing,while those with the diameter <45 μm near the wafer’s surface and those <5 μm and >25 μm inside increased notably after annealing.The reason for the above variation was de-termined by Te inclusions migration along the direction of temperature gradient.And during the migration,Te inclusions grew via incorporating with those with similar diameter and Ostwald ripening among those with com-paratively different diameter.But the ripening was not sufficient so that many smaller Te inclusions remained in the annealed samples.