Tuning the polarization-induced free hole density in nanowires graded from GaN to AlN
Abstract
We report a systematic study of p-type polarization-induced doping in graded AlGaN nanowire light emitting diodes grown on silicon wafers by plasma-assisted molecular beam epitaxy. The composition gradient in the p-type base is varied in a set of samples from 0.7%Al/nm to 4.95%Al/nm corresponding to negative bound polarization charge densities of 2.2 × 1018 cm−3 to 1.6 × 1019 cm−3. Capacitance measurements and energy band modeling reveal that for gradients greater than or equal to 1.30%Al/nm, the deep donor concentration is negligible and free hole concentrations roughly equal to the bound polarization charge density are achieved up to 1.6 × 1019 cm−3 at a gradient of 4.95%Al/nm. Accurate grading lengths in the p- and n-side of the pn-junction are extracted from scanning transmission electron microscopy images and are used to support energy band calculation and capacitance modeling. These results demonstrate the robust nature of p-type polarization doping in nanowires and put an upper bound on the magnitude of deep donor compensation.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 19, 2015
- Source ID
- 10.1063/1.4906449
Entities
People
- A. T. M. Golam Sarwar
- David W McComb
- Fan Yang
- Roberto C. Myers
- Santino D. Carnevale
- Thomas F. Kent
Organizations
- Army Research Office
- National Science Foundation
- Ohio State University