PT Unknown AU Verevkin, AA Ptitsina, NG Smirnov, KV Goltsman, GN Gershenson, EM Yngvesson, KS TI Direct measurements of electron energy relaxation times at an AlGaAs/GaAs heterointerface in the optical phonon scattering range SE Proc. 4-th Int. Semicond. Device Research Symp. PY 1997 BP 55 EP 58 DE 2DEG; AlGaAs/GaAs heterostructures ER