THz response of GaAs/AlGaAs superlattices: from classical to quantum dynamics

✍ Scribed by S. Zeuner; B.J. Keay; S.J. Allen; K.D. Maranowski; A.C. Gossard; U. Bhattacharya; M.J.W. Rodwell

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 98 KB
• Volume: 22
• Category: Article
• ISSN: 0749-6036
• DOI: 10.1006/spmi.1996.0288

✦ Synopsis

We have investigated the THz response of a series of GaAs/Al x Ga 1-x As superlattices with a variety of miniband widths. The samples range from the sequential resonant tunneling limit with a very narrow miniband to superlattices with a miniband width of 20 meV. The sequential tunneling superlattices show a transition from classical rectification at frequencies below 600 GHz to quantum response above 1 THz. In the quantum regime, the I -Vs show distinct peaks due to absorption and stimulated emission of up to seven THz-photons. At high a.c. field strengths (several kV cm -1 ) the photon-assisted channels dominate the transport, leading to dynamic localization, absolute negative conductance, and gain just below the Stark splitting of the quantum well ground-states. The transition from classical to quantum behavior takes place at a frequency where hω ∼ , where ≈ 2 meV is the ground-state level width in a single quantum well.