We report our research on processing of AlGaAs/GaAs structures for THz quantum-cascade lasers (QCLs). We focus on the processes of fabrication of Ti/Au claddings for metal-metal waveguides and the wafer bonding with indium solder. We place special emphasis on the optimum technological conditions of these processes, leading to working devices. The wide range of technological conditions was studied, by use of test structures and analyses of their electrical, optical, chemical and mechanical properties, performed by electron microscopic techniques, energy dispersive X-ray spectrometry, secondary ion mass spectroscopy, atomic force microscopy, fourier-transform infra-red spectroscopy and circular transmission line method. On the basis of research a set of technological conditions was selected, and devices lasing at the maximum temperature 130K were fabricated from AlGaAs/GaAs structures grown by molecular beam epitaxy (MBE) technique. Their threshold-current densities were about 1.5kA/cm². Additionally we report our initial stage research on fabrication of Cu-based claddings, that theoretically are more promising than the Au-based ones for fabrication of low-lossy waveguides for THz QCLs.

Date Published: 5 September 2014
PDF: 15 pages
Proc. SPIE 9199, Terahertz Emitters, Receivers, and Applications V, 919903 (5 September 2014); doi: 10.1117/12.2061997

Published in SPIE Proceedings Vol. 9199:
Terahertz Emitters, Receivers, and Applications V
Manijeh Razeghi; Alexei N. Baranov; John M. Zavada; Dimitris Pavlidis, Editor(s)