Hole mobility limiting factors in dopant-free p-type distributed polarization-doped AlGaN

Abstract

We investigated the hole mobility limiting factors in dopant-free p-type distributed polarization-doped (DPD) AlGaN layers by an experimental method. p-DPD AlGaN exhibited a higher hole mobility than GaN:Mg with a similar room temperature hole concentration across all temperature ranges owing to the absence of ionized impurity scattering. In addition, unlike in n-DPD AlGaN, alloy scattering was not always critical in p-DPD AlGaN. The extracted alloy scattering potential was only 0.3 eV, which resulted in a reduced effect of alloy scattering and originated from a small valence band offset in the GaN/AlN heterojunction system. The results suggest that DPD principally enables the fabrication of low-resistance p-type nitride semiconductor thin films as a result of the high hole concentration and high hole mobility.

Demonstration of AlGaN-on-AlN p-n Diodes With Dopant-Free Distributed Polarization Doping

“…This approach presents a promising solution to the challenges of conductivity control in AlN-based materials. To date, we have extensively studied GaN-based vertical p-n diodes (PNDs) formed by dopant-free DPD and demonstrated excellent electrical properties such as ideal breakdown electric field, high hole mobility, as well as longer electron lifetime and larger diffusion coefficient than those of p-GaN:Mg [16], [17], [18]. Moreover, our group employed DPD for the p-type cladding layer of an AlN-based laser diode to increase its conductivity and transparency.…”