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Title: Tuning the polarization-induced free hole density in nanowires graded from GaN to AlN

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 × 10{sup 18 }cm{sup −3} to 1.6 × 10{sup 19 }cm{sup −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 × 10{sup 19 }cm{sup −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.
Authors:
;  [1] ; ; ;  [2] ;  [1] ;  [3]
  1. Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)
  2. Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)
  3. (United States)
Publication Date:
OSTI Identifier:
22415135
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 3; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ALUMINIUM NITRIDES; CAPACITANCE; CHARGE DENSITY; CONCENTRATION RATIO; GALLIUM NITRIDES; LIGHT EMITTING DIODES; MOLECULAR BEAM EPITAXY; NANOWIRES; POLARIZATION; SEMICONDUCTOR JUNCTIONS; SILICON; TRANSMISSION ELECTRON MICROSCOPY