Molybdenum News Center

Nitridation of And Sapphire Substrate Effect on The Growth of GaN Layer at Low Temperature

A remote plasma enhanced-ultrahigh vacuum chemical vapor deposition system equipped with a radio frequency (RF) – inductively coupled plasma which produces the reactive nitrogen species was employed to grow GaN layers at low temperature. The X-ray photoelectron spectroscopy analysis of nitrogen composition on the nitridated substrate surface indicated that the nitridation process on the substrate surface is largely affected by RF power at low temperature. However, the atomic force microscope images indicated that the protrusion density on the nitridated sapphire surface is critically dependent on the nitridation temperature. It was possible to nitridate the sapphire surface without the production of protrusions by controlling the RF power and nitridation temperature even at low temperatures. The crystallinity of the GaN grown at 450°C was found to be much improved when the sapphire substrate was nitridated at low temperature prior to the GaN layer growth. Moreover, lateral growth of the GaN layer was enhanced not only by an increase in growth temperature but also by the nitridation of sapphire substrate prior to the GaN layer growth.

The grooved c -plane sapphire substrates were first systematically investigated by wet chemical etching, with H2SO4 and a 3H2SO4:1H3PO4 mixture as the etchants. The structural and morphological characteristics of the grooved sapphire with mask stripes along the directions, respectively, were studied under different etching time and temperatures by scanning electron microscopy (SEM). Two kinds of groove shapes are obtained. One is a V-groove whose two sidewalls are both formed by a single facet. The other is a U-groove whose one sidewall consists of two or three facets, and the other sidewall is composed of a single facet. SEM cross-sectional images show symmetrical sidewall facets with stripes along the sapphire direction and asymmetrical sidewall facets with stripes along the sapphire direction. The etching depth is linear with the etching time. The activation energies of etching reaction are evaluated in the temperature range 340–400°C . It is confirmed that sapphire with stripes along the direction is suitable for lateral epitaxial overgrowth of low-threading-dislocation GaN films.


More molybdenum product: http://www.molybdenum.com.cn
Tel: 0592-5129696 Fax：0592-5129797
E-mail:  This email address is being protected from spambots. You need JavaScript enabled to view it.
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Tungsten News & Tungsten Price: http://www.chinatungsten.com

• < Prev
• Next >