High temperature annealing of undoped and Mn doped InP: photoluminescence and Hall measurements

Abstract

PACS 72.80. Ey, 78.55.Cr Crystals of intentionally undoped n-type InP and Mn doped p-type InP were grown by the Czochralski technique. The as-grown crystals and those processed by high temperature long time annealing were studied by low temperature photoluminescence and temperature dependent Hall measurements. A new broad band was observed in those undoped InP samples which were converted to semi-insulating state by annealing. Hall measurements on those samples show that the semi-insulating state is caused by deep level defects of the same energy as the binding energy of the Fe impurity. Another new photoluminescence band appeared in the annealed InP doped with Mn, while the concentration of Mn did not change according to both photoluminescence and Hall measurements.Introduction Semi-insulating (SI) InP is a very important material for high-frequency devices and for applications in optoelectronics. Up till now, SI InP could only be obtained via doping by transition metal (TM) impurities such as Fe, Co, Cr and Mn [1-3] which act as deep acceptors and by co-doping by Ti and Zn, which act as a deep donor and a shallow acceptor, respectively. However, conventional TMdoped InP has various disadvantages. It is preferable to avoid TM doping since it is possible that these impurities may deteriorate device performance [4]. Undoped SI InP, which can be realised by hightemperature annealing, is a candidate for replacing conventional TM-doped InP by a material of better quality. There are several reports in the literature on the realisation of nominally undoped SI InP [5 -7] with promising results but it is not clear if deep defects were created as in the case of undoped SI GaAs. To understand the mechanism of the conversion (due to annealing), we have measured samples of undoped InP after annealing, by temperature dependent Hall measurements and by low-temperature photoluminescence (PL). Further, we have measured the effect of annealing on p-type Mn doped InP.

Characteristics of photoluminescence and Raman spectra of InP doped silica fiber

“…We think that the broadband emission would be probably caused by the recombination of the deep levels from the introduction of InP. Because InP was vaporized in the fiber by the high temperature after suffering from an annealing process in the drawing process, deep level defects are easily generated in ambient of ion P and Fe [16,17]. The broadband emission centered at around 1.08 eV, starting from the typical InP band edge, was well coincided with that reported in bulk InP [18] and In 0.7 Ga 0.3 P/InP structure [19] and the defect center model for the broadband emission [20], in which the recombination of deep level was characterized as such broadband emission.…”