Terahertz time-domain ellipsometry with high precision for the evaluation of GaN crystals with carrier densities up to 1020 cm-3.
Sci Rep
; 11(1): 18129, 2021 Sep 15.
Article
in En
| MEDLINE
| ID: mdl-34526558
ABSTRACT
Gallium nitride (GaN) is one of the most technologically important semiconductors and a fundamental component in many optoelectronic and power devices. Low-resistivity GaN wafers are in demand and actively being developed to improve the performance of vertical GaN power devices necessary for high-voltage and high-frequency applications. For the development of GaN devices, nondestructive characterization of electrical properties particularly for carrier densities in the order of 1019 cm-3 or higher is highly favorable. In this study, we investigated GaN single crystals with different carrier densities of up to 1020 cm-3 using THz time-domain ellipsometry in reflection configuration. The p- and s-polarized THz waves reflected off the GaN samples are measured and then corrected based on the analysis of multiple waveforms measured with a rotating analyzer. We show that performing such analysis leads to a ten times higher precision than by merely measuring the polarization components. As a result, the carrier density and mobility parameters can be unambiguously determined even at high conductivities.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Sci Rep
Year:
2021
Type:
Article
Affiliation country:
Japan