|Ph.D Student||Albo Asaf|
|Subject||GaInAsN/(A1)GaAs Quantum-Well-Based Structures:|
Growth, Physical Properties and IR-Devices
|Department||Department of Electrical and Computer Engineering||Supervisors||PROFESSOR EMERITUS Gad Bahir|
|ASSOCIATE PROF. Dan Fekete|
Mixed-anion III-V-N (dilute-nitrides) alloys exhibit a huge bowing in the band gap-energy, for example, the addition of only 1 % of nitrogen to GaAs causes a dramatic decrease in band-gap energy by about 0.1-0.15 eV. The physical origin of III-V-N's unique properties is attributed to the interaction of the conduction-band-extended-states with the localized nitrogen-states as described by the band-anti-crossing-model proposed by Shan et al. The remarkable fundamental properties of GaInAsN quaternary alloy, in combination with the possibility to control the lattice constant of the alloy material in a wide range by changing the N content, provide an opportunity to tailor the material properties for desired applications in optoelectronic devices.
The growth of optoelectronic devices based on GaInAsN material (in particular by metal organic chemical vapor deposition- MOCVD) has been a new challenge for the research in epitaxial growth. In this work we implemented unique new approaches to the growth of dilute nitrides using MOCVD. We developed a two-step nitrogen flow process which compensates the decrease in nitrogen incorporation during QW growth. Using this growth process we grew high quality GaInAsN/GaAs QWs with emission wavelength in the range of 1.3 micron at room temperature. In addition, we developed a novel strain controlled atomic layer epitaxy (ALE) growth process. We employed this technique for the growth of InAsN/GaAs short-period-superlattice (SPSL) structure suitable for applications in optical communication. Based on this method we grew and characterized an improved hole confinement bi-layer, InAsN/GaAsSbN, type II quantum structure suitable for high-temperature-characteristics near IR lasers.
A quantum-well infrared photodetector (QWIP) based on a GaInAsN/(Al)GaAs standard multiple-quantum well (MQW) structure was fabricated. The intersubband photocurrent spectrum at 300 K peaked at ~1.4 μm and demonstrates polarization independent response and high gain and responsivity beyond the record of standard III-V based QWIPs. Using a 10 band k?p model (including the band anti-crossing) we can attribute these results to a long-lifetime new type of bound-state-in-the-continuum.