Bandgap Tuning of InSb by Chemical Doping

The growth of InAsSb crystal by using the Bridgeman method is reported, and the structural, optical and electric characterizations of the crystal are depicted. It is found that the (111) X-ray diffraction peak exhibits a shift towards the higher-angle side, accompanied by a notable broadening of the peak width. According to the Vegard law, the As doping concentration of the sample can be calculated, which agrees well with the result obtained by energy-dispersive X-ray spectroscopy. Moreover, the substitution of Sb by As results in an observable increase of the background carrier concentration of the material system. The As doping can also severely influence the optical properties of InSb, leading to a distinct reduction of the bandgap as revealed by the measurements of Fourier transform infrared transmission spectra. The bandgap derived by fitting the (αd)²-hν plot is in agreement with the value obtained by the Woolley-Warner relationship. Our results show that As doping is a feasible way for the realization of long-wavelength infrared InSb-based detectors.