ELECTRON INTERSUBBAND TRANSITIONS TO 0.8 EV (1.55 MU-M) IN INGAAS ALAS SINGLE QUANTUM-WELLS

We report a polarization-resolved infrared absorption study of the qua ntum-well-width dependence of the electron intersubband transitions in strained InGaAs/AlAs single quantum wells (SQWs) 3, 4, and 5 monolaye rs (ML) in width. An intersubband transition energy as high as 0.8 eV (i.e., a wavelength as short as 1.55 mum) is observed with transverse magnetic field polarization for a 3-ML-thick InGaAs SQW. This is the h ighest quantum-well intersubband transition energy ever reported in an y materials system.