Optical Properties of Zn{sub}0.46Cd{sub}0.54Se/Zn{sub}0.24Cd{sub}0.25Mg{sub}0.51Se Multiple Quantum Wells for Infrared Photodetector Applications

摘要

Recently, lattice-matched Zn{sub}0.46Cd{sub}0.54Se/ZnCdMgSe multiple-quantum-wells (MQWs) have been recognized as very promising materials to fabricate intersubband (ISB) devices such as quantum cascade lasers and mid-infrared photoconductors. These structures have important applications in biological and chemical detections. The ISB transition covers a wide mid-infrared wavelength range from 1.3μm to a few tens of μm. In this work, two heavily doped n-Zn{sub}0.46Cd{sub}0.54Se/Zn{sub}0.24Cd{sub}0.25Mg{sub}0.51Se MQW structures have been grown on InP (001) substrate by molecular beam epitaxy. Temperature dependent steady-state photoluminescence (SSPL), temperature dependent time- resolved photoluminescence (TRPL), and Fourier transform infrared spectroscopy (FTIR) were performed to characterize their interband and ISB properties. These two MQW samples have similar structures except different well widths and different number of periods. The integrated SSPL intensities and the PL decay times of the MQWs were measured as functions of temperature in the range from 77K to 290K. The luminescence efficiency of the sample with 28A well width is larger than that of the sample with 42A well width although both samples exhibit similar temperature dependence of PL intensity. Time-resolved PL measurements show that the PL decay times of both samples decrease with increasing temperature. From 77K to 290K, the decay time of the sample with 28A well width is in the range of 440ps～120ps and is much longer than that of the sample with 42A well width, which is in the range of 65ps～25ps. Strong non-radiative recombinations dominate the luminescence behavior of the wider MQWs. Intersubband absorption spectra of the samples were measured by FTIR and show peak absorption at wavelengths of 3.99μm and 5.35μm for the MQWs with well widths of 28A and 42A, respectively, falling within the 3-5μm range, which is of great interest for the infrared photodetector applications.