Beyond Quantum Efficiency Limitations Originating from the Piezoelectric Polarization in Light Emitting Devices

Blue and violet light emitting devices based on III-nitrides caused an ongoing revolution in general lighting. One of the highly deliberated discussions in this field is devoted to the problem called the “green gap” which is a lack of efficient emitters in this spectral regime. One of the reasons behind the insufficient internal quantum efficiency (IQE) of green III-nitride devices is related to the quantum confined Stark effect. In this paper we present a counterintuitive feature of quantum well systems with large built-in electric field which leads to a huge enhancement in IQE. We show, by means of numerical simulations, that an increase of the InGaN quantum well thickness initially leads to a decrease of the oscillator strength, however, after a certain critical thickness is reached, highly efficient recombination path appears via excited states. A peculiar quantum well system with a zero-probability transition between the ground states and an extremely high one through the excited states is demonstrat...