Abstract

Intersubband absorption of electrons in quasi-2-D semiconductor structures has received much attention from a fundamental physics point of view and for semiconductor devices. Here we study—on a picosecond time scale—transient intersubband absorption spectra of hot electrons in an n-type modulation doped Ga_0.47In_0.53As/Al_0.48In_0.52As MQW structure grown by molecular beam epitaxy [quantum well (QW) thickness, 8.2 nm; electron density, 4.2 × 10¹¹ cm⁻²/QW]. Electron-hole pairs with an excess energy of 0.3 eV are generated by picosecond interband excitation in the near IR (excitation density, N ≃ 2×10¹¹ cm⁻²).

© 1990 Optical Society of America