Xt–Xlvalley crossover and deformation potential in AlP/GaP quantum wells

Abstract

We investigate the properties of quasi-two-dimensional electrons in a wide range of modulation-doped AlP quantum wells ͑between 3 and 15 nm͒ with GaP barriers by measuring cyclotron resonance, quantum Hall effect, and Shubnikov-de Haas oscillations. The degeneracy of the three X valleys is lifted due to both strain and confinement: In wider wells the strain contribution dominates, and the lowest energy states are the transverse X valleys X t . On the other hand, in narrower wells, the quantum confinement energy dominates, and the lowest energy states are the single longitudinal valleys X l . The transition between these two configurations occurs for wells between 5 nm and 4. The effective mass components for the AlP X valleys are determined from the cyclotron resonance data to be m t = ͑0.30Ϯ 0.01͒m 0 and m l = 0.90m 0 . From these effective mass values and the degeneracy data, we calculate the deformation potential for AlP to be ⌶ u AlP = 3.3Ϯ 0.5 eV.

Light emission despite doubly-forbidden radiative transitions in AlP/GaP quantum wells: Role of localized states

“…For simplicity, the strain-induced splitting of the three-fold degenerate X-valley of AlP is not shown. 15,16 It is important to note that there will be an electrostatically produced band-bending. 17 This will be especially important for the holes in the GaP layer.…”