Intersubband Optical Transitions in Ultra-Wide Bandgap Quantum Well Structures*

Nanoscale quantum structures form the basis for several technological breakthroughs such as light emitting diodes and night vision devices. In this work, we theoretically explore the optical intersubband transitions in ultra-wide band gap Gallium Oxide/ Aluminum Gallium Oxide heterostructures for infrared detection and resonant tunneling effects. Gallium Oxide is an emerging ultra-wide band gap material with a range of potential applications in electronics and optoelectronics. The main advantage of this material system stems from the availability of large area high quality bulk substrates grown using potentially inexpensive melt-based techniques. The other major advantage of beta-phase Gallium Oxide is the absence of spontaneous and piezoelectric polarization. In this work, we exploit the lack of polarization to engineer intersubband optical transitions in quantum well structures. Energy band diagrams and wavefunction solutions of quantum wells are obtained using a Schrödinger -Poisson solver. Optical transition rates are numerically estimated using fermi golden rule and overlap integrals. This theoretical work is a first step towards exploring Oxide heterostructures for high performance infrared devices and resonant tunneling diodes.