Contactless Electroreflectance Study of a GaAIAs/lnGaAs/GaAs/GaAIAs Step Quantum Well Structure

摘要

Using contactless electroreflectance at 300 and 77K, we have studied the inter-subband transitions from a GaAlAs/InGaAs/GaAs/GaAlAs step quantum well structure (small well inside a large well) consisting of two layers A (In_xGa_(1-x)As) and B (GaAs) with widths L_A and L_B, respectively, bounded by two thick barrier regions of Ga_(1-y)Al_yAs. By comparison of the observed spectral features with an envelope function calculation, including the effects of strain, we have been able to characterize the potential profile of the structure, i.e., L_A, L_B, x, and y. There is very good agreement between experiment and the intended materials parameters. Such configurations are of considerable importance since (a) they form the basis for pseudomorphic high electron mobility transistors, and (b) also have applications in optoelectronics due to their large Stark shifts.