Date of Award

3-21-2013

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Engineering Physics

First Advisor

Stephen R. McHale, PhD.

Abstract

The Schottky barrier height (SBH) was measured on GaN based diodes with three different dopant types; Gd, Er and Yb. Two methods were used to determine the SBH. The first method was the Juergen Werner method to evaluate the I-V characteristics. The calculated SBH of the diodes using this method was 1.41 ± 0.20eV, 1.71 ± 0.25eV and 1.75 ± 0.28eV for the Gd-, Er- and Yb-doped diodes respectively. It was observed that using an ad-hoc effective Richardson constant value of 0.006Axcm-2xK-2 to calculate the SBH rendered results that were in no greater than 2% disagreement (neglecting error) with photoemission spectroscopy measurements performed on the same GaN thin films by a another researcher a year prior. The second method of measuring the SBH was the temperature dependent I-V-T measurements using the modified Norde function. The calculated SBH of the diodes were universally lower than the results of the Juergen Werner method. The SBH was 1.19 ± 0.12eV, 1.39 ± 0.16eV and 1.43± 0.12eV for the Gd-, Er- and Yb-doped diodes respectively. Additionally, the Norde method provided direct calculation of the effective Richardson constants, which were 0.011 ± 0.001Axcm-2xK-2, 0.036 ± 0.003Axcm-2xK-2 and 0.021 ± 0.02Axcm-2xK-2 for the Gd-, Er- and Yb-doped diodes respectively. Both measurements in this study are in agreement with the earlier photoemission spectroscopy measurements with regard to the proportional differences among the different dopant types.

AFIT Designator

AFIT-ENP-13-M-03

DTIC Accession Number

ADA582470

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