Efficiency enhancement in InGaN-based laser diodes using an optimized Al0.12Ga0.88N electron blocking layer

Abstract

In this paper, a design for an electron blocking layer (EBL) is proposed to enhance the wall plug efficiency of InGaN-based laser diodes. Using calibrated 3D simulations (including thermal models), a comprehensive analysis of various design aspects (composition, thickness and p-doping) of EBLs is conducted, including their impact on carrier (electron and hole) wavefunction overlap and stimulated recombination rate in the quantum wells (QWs) along with the space charge density, electric field and free carrier absorption (FCA) at the interface of the p-side waveguide/EBL. The results indicate that Poole–Frenkel emission is vital for consideration of FCA in the p-doped layers of the epitaxial structure. Consequently, the proposed EBL design reduces electron overflow, improves hole injection, decreases the internal absorption losses and thus, enhances the internal quantum efficiency of the device. The threshold current is reduced from 230 mA to 205 mA as compared to the reference structure. The hole barrier is reduced by 23.93%. Hence, the output power is increased from 1.746 W to 1.95 W, and the voltage drop as well as the device temperature is reduced. These improvements enhance the efficiency from 37.4% of the reference structure to 42.1% in the proposed structure (corresponding to a bias current of 1 A).