Development and characterization of an atomic nitrogen source for the epitaxial growth of GaN
Abstract
An efficient atomic nitrogen source based on a N2 surface-wave discharge has been developed and was characterized using optical spectroscopy. The production of atomic nitrogen was measured by NO titration as a function of various discharge parameters such as the applied field frequency (f=13.56, 40.68, 440 and 2450 MHz) and the absorbed power (PA = 20 to 200 W). Dissociation rates ([N]/[N_2]) as high as 1.7% were obtained at a source pressure of ps = 4 torr, f = 440 MHz and PA = 100 W. The N2 rotational and vibrational temperatures were also measured in the discharge. It was found that the saturation of [N]/[N_2] with increasing PA at ps = 4 torr occurs at a threshold gas temperature of about 500 K for all values of f. This atomic nitrogen source was used together with a pulsed laser deposition system for the epitaxial growth of GaN on the sapphire(0001) substrate, with a cooled Ga target being used as a gallium source. High quality GaN thin films were deposited by optimizing both the laser intensity and the nitrogen flux. To date, our best GaN films show a FWHM of the GaN(0002) rocking curve peak equal to 200 arcsec.This result was obtained with a substrate temperature of 800^oC and under Ga-rich growth conditions.
- Publication:
-
APS Annual Gaseous Electronics Meeting Abstracts
- Pub Date:
- October 1999
- Bibcode:
- 1999APS..GEC.FW103M