Characterization of high-purity InP by photoluminescence

Abstract

InP polycrystals grown by the HB technique and InP single crystals grown by the liquid-encapsulated Czochralski technique have been evaluated by photoluminescence. It was found that as the carrier concentration is decreased, the photoluminescence spectrum shows finer structures. When the carrier concentration is less than 9×1014 cm−3, a strong free-exciton peak could be observed.

Semi-Insulating Behavior of InP Wafers Prepared by Phosphorus Vapor Pressure Controlled Wafer Annealing

“…Inoue annealing at 620 C and the carrier concentrations slightly increased at temperatures higher than 720 C under phosphorus vapor pressure of 0.05 MPa. They suggested that phosphorus vacancies were significantly formed by annealing at temperatures higher than 720 C under phosphorus vapor pressure of 0.05 MPa [16]. This result shows similar tendency to the transport properties of slightly Fe doped InP as shown in Fig.…”

“…Table 1 shows the electrical properties of undoped InP wafers before and after annealing. Undoped InP crystals are usually of n-type conductivity and have native defects which are predominated by phosphorus vacancies as reported by Inoue et al [16]. The carrier concentrations in undoped InP before annealing were in the range of (3.0-5.0) Â 10 15 cm --3 and decreased to the range of (1.1-2.9) Â 10 14 cm --3 after annealing at 950 C under atmospheric phosphorus vapor pressure, which were one order of magnitude lower than those of as-grown crystals.…”

“…The dominant shallow donor type defect is considered as phosphorus vacancy from Puska's calculations [17]. The dominant shallow acceptor impurity can be regarded as Zn from the results of photoluminescence spectra measured by Inoue et al [16,18] and N a is less than about 1 Â 10 14 cm --3 [16,19]. Since Fe acts as deep acceptors in InP, the Fe doping is effective for compensating shallow donors.…”

“…For consideration of the compensation mechanism, the Shockley diagram is convenient [19,22,23,29,30]. In the case of slightly Fe doped SI InP, it is considered that there are mainly three levels, that is, shallow donors due to phosphorus vacancy [16,17], shallow acceptors due to Zn [16,18,19], deep acceptors due to Fe [19,31]. Although Si can be considered as residual impurity, the Si concentration is under the detection limit of GDMS (< 5 Â 10 14 cm --3 ).…”

“…Although Si can be considered as residual impurity, the Si concentration is under the detection limit of GDMS (< 5 Â 10 14 cm --3 ). Because InP polycrystals were synthesized by the HB (Horizontal Bridgmann) method using a pBN (pyrolytic boron nitride) boat instead of SiO 2 boats [18,32], InP single crystals were purified by the gettering effect of the B 2 O 3 encapsu- [18] and Si remained in the InP melt during crystal growth due to impurity segregation [11,32]. Furthermore, the deep levels of phosphorus related defects have been reported by several authors.…”