We demonstrate n-type doping of GaN with Ge by MOCVD at high concentrations that are necessary to fully screen the polarization fields in c-plane InGaN/GaN quantum wells. Hall measurements show linear Ge incorporation with dopant flow rate and carrier concentrations exceeding 1×10 cm. GaN:Ge layers exhibit excellent electron mobility, high conductivity, and contact resistivity comparable to the best unannealed contacts to Si-doped GaN. However, the surface morphology begins to degrade with Ge concentrations above 1×10 cm, resulting in severe step bunching and a network of plateaus and trenches, even in layers as thin as 10 nm.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was supported by the KACST-KAUST-UCSB Solid State Lighting Program (SSLP). Additional support was provided by the Solid State Lighting and Energy Electronics Center (SSLEEC) at UCSB. A portion of this work was done in the UCSB nanofabrication facility, part of the NSF NNIN network (ECS-0335765), as well as the UCSB MRL, which is supported by the NSF MRSEC Program (DMR-1121053). The sapphire substrates, freestanding GaN substrates, and the IBGe metalorganic source used for this study were provided by Namiki Precision Jewel, Furukawa Denshi Co., Ltd., and Dow Chemical Co., respectively.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.