Normal incidence detector using Ge quantum-well structures grown on Si (100)

Summary form only given. The normal incidence detection of light by Sb δ-doped Ge/Si_1-xGe_x multiple quantum well (MQW) structures grown on Si(100) substrates has been demonstrated. The observation of strong electron intersubband infrared absorption for δ-doped Ge/Si_1-xGe_x MQW structures grown on Si (100) substrates is reported. The principle is to use tilted ellipsoids of Ge L valleys to obtain normal incidence transition. The structure is grown by Si molecular beam epitaxy (Si-MBE) and Sb is doped by thermal evaporation. The intersubband absorption is shown to be allowed for the optical field components both perpendicular and parallel to the quantum wells due to the tilted ellipsoids of constant energy surfaces