The impact of many-body effects on the properties of β-(AlGa)2O3/Ga2O3 quantum cascade structure

Abstract

The impacts of many-body effects, which include the Hartree potential, exchange-correlation potential, depolarization effect, and excitonic effect, on the n-type periodic β-(Al0.3Ga0.7)2O3/Ga2O3 quantum cascade structure with four quantum wells of different widths have been theoretically investigated. The conduction band structure and wave functions of the device were obtained by iteration of the Schrödinger and Poisson equations to describe the bound-to-bound electronic transport processes. The results show that the many-body effects make a significant contribution to the energy band parameters, especially the energy level and wave function of subbands in the active wells. By considering many-body effects, the peak absorption coefficient increases from 6.14 × 10−4 to 1246.93 cm−1. The depolarization and excitonic effects lead to a peak response wavelength shift of approximately 1.33 μm. When the temperature increases from 77 to 300 K, the peak responsivity of the long wavelength infrared β-(AlGa)2O3/Ga2O3 quantum cascade detector (QCD) only decreases 22.87% and the peak response wavelength remains almost constant, indicating an excellent temperature stability. Moreover, the room-temperature dark current of proposed QCD is 1.46 × 10−15 A, which is much lower than that of QCDs based on some materials and operating at similar wavelengths. This work would benefit the research and development of β-(AlGa)2O3/Ga2O3 QCDs.