Theory and Design of Electron Blocking Layers for III-N Based Laser Diodes by Numerical Simulation

Abstract

Unlike laser diodes made of traditional III-V materials (III-AsP), III-Nitride laser diodes and LEDs suffer from reduced injection efficiency due to greater electron leakage [1]. The overflow of electrons out of the active region into the adjacent p-type quasi-neutral region (QNR) is primarily due to the asymmetry between majority carrier conductivities in p- and n-GaN [2], where the electron conductivity in n-GaN is more than 40 times greater than the hole conductivity in p-GaN [3], [4]. Furthermore, carrier leakage is exacerbated by interfacial spontaneous and piezoelectric polarization charges at III-N heterojunctions. To stem electron leakage, an electron blocking layer (EBL) is typically employed between the last quantum barrier (QB) and p-type quasi-neutral region (QNR), and this EBL is typically a thin layer of wide bandgap material.