Optical quality improvement of InGaAs/AlAs/AlAsSb coupled double quantum wells grown by molecular beam epitaxy

Abstract

Intersubband optical transitions at short wavelengths in strain-compensated In 0.70 Ga 0.30 As-AlAs double quantum wells are investigated by means of mid-infrared absorption. Trade-offs between achieving a high transition energy and a large oscillator strength of the two highest-energy intersubband transitions using our strain-compensation approach are analyzed as a function of the widths of the two wells. Two design strategies leading to relatively strong intersubband optical transitions at 800 meV, 1.55 m, are described and the corresponding structures grown using gas-source molecular-beam epitaxy on ͑001͒InP are investigated. The strongest intersubband transitions obtained experimentally are generally between 300 and 600 meV, 2 -4 m. Significant oscillator strength, however, also extends out to 800 meV, 1.55 m.

Growth of InGaAs/AlAsSb single quantum wells with various AlAs diffusion-stopping layers

“…We also demonstrated that the absorption response time was greatly reduced to 690 fs when InGaAs/AlAs/ AlAsSb coupled double quantum wells (C-DQWs) were used [6]. Our most recent study indicates that the application of AlAs diffusion-stopping layers to C-DQWs significantly improves ISBT properties with respect to both Is and response time [7,8]. However, this sample had many cross-hatched lines and its X-ray diffraction (XRD) rocking curve had broad satellite peaks.…”