The mode splitting induced by electro-optic birefringence in a P–I–N InGaAs/GaAs/AlGaAs vertical-cavity surfaceemitting laser(VCSEL)has been studied by polarized electroluminescence(EL)at room temperature.The polarized EL spectra with E[110]and E[1ˉ10]directions,are extracted for different injected currents.The mode splitting of the two orthogonal polarized modes for a VCSEL device is determined,and its value increases linearly with the increasing injected current due to electro-optic birefringence.This article demonstrates that the polarized EL is a powerful tool to study the mode splitting and polarization anisotropy of a VCSEL device.
Ag- and Sn-doped In2S3 thin films were deposited on glass substrates using the thermal evaporation technique. The doping was realized by thermal diffusion. The influences of Ag and Sn impurities on the electrical, structural, morphological, and optical properties of the In2S3 films were investigated. In all deposited samples, the x-ray diffraction spectra revealed the formation of cubic In2S3 phase. A significant increase in the crystallite size was observed after Ag doping,while the doping of Sn slightly decreased the crystallite size. The x-ray photoelectron spectroscopy verified the diffusion of Ag and Sn into the In2S3 films after annealing. The optical study illustrated that Ag doping resulted in a reduction of the optical band gap while Sn doping led to a widening of the gap. Optical properties were investigated to determine the optical constants. Besides, it was found that the resistivity decreases significantly either after Ag or Sn incorporation. The study demonstrates that the Sn-doped In2S3 thin films are more suitable for buffer layer application in solar cells than the Ag-doped In2S3 thin films.
