(CdTe)_m(ZnTe)_n-ZnTe多量子阱结构的静压光致发光和共振喇曼散射研究

Photoluminescence and Resonant Raman Scattering from(CdTe)_m(ZnTe)_n-ZnTe Structure under Hydrostatic Pressure

(CdTe)_m(ZnTe)_n-ZnTe多量子阱是由(CdTe)_m(ZnTe)_n短周期超晶格限制在ZnTe势垒中组成的新结构。它可以提高CdTe/ZnTe异质生长的临界厚度。静压下的光致发光研究表明加压后(CdTe)_m(ZnTe)_n超晶格和ZnTe势垒层的光致发光峰分别以8.80和 9.47meV/kbar的速率向高能移动。利用这种静压下的带隙变化,实现了与514.5和488.0nm激发光的共振喇曼散射。观察到高达4阶的多声子共振喇曼散射。并发现与(CdTe)_m(ZnTe)_n超晶格共振时的类ZnTe LO声子模频率比与ZnTe热垒共振时的ZnTe LO声子频率低1.4cm^(-1)。反映了在(CdTe)_m(ZnTe)_n超晶格中LO声子的局域效应。

The photoluminescence of (CdTe)_m/(ZuTe)_n strained quantum wells with m=4, 8 and 12monolayer has been studied at 77 K under hydrostatic pressure up to 50 kbar. At atmosphericpressure, the luminescence peaks of wells with m=8 and 12 are significantly broader than thatof well with m=4, indicating that the strain in wells with m=8 and 12 has relaxed. It is ingood agreement with the calculation results based on the Kronig-Penney model. No furtherbroadening was observed in the measured pressure range. The pressure coefficients of luminescencepeaks increase from 6.81 meV/kbar of m=12 well to 8.24 meV/kbar for well withm=4. Calculation taking into account the pressure induced modifications of the barrier height,effective masses and well width demonstrated that the increase of the barrier height withpressure is the main reason for the increase of the pressure coefficient, with reduced wellwidth.