X-GAMMA INDIRECT INTERSUBBAND TRANSITIONS IN TYPE-II GAAS ALAS SUPERLATTICES/

Intersubband transitions indirect in both real and momentum spaces wer e observed in GaAs/AlAs type II short period superlattices. Significan t absorption of normal incident radiation, with ''forbidden'' polariza tion was measured, in addition to absorption in the ''allowed'' config uration. The transition energy shows a strong temperature dependence. This absorption is attributed to X-T transition. Both doped and undope d samples were investigated. Normal incidence absorption is stronger f or the doped superlattices. Simulations using a two band model show go od agreement to experimental data. (C) 1996 American Institute of Phys ics.