Growth of high-temperature AlN
layers on sapphire substrates
using ammonia MBE
Grishchenko, I. S. Ezubchenko, M. L. Zanaveskin, I. O. Mayboroda, M.Y u.
research centre "Kurchatov institute"
The paper is received on December 30,
Epitaxial films and III-nitrides heterostructures
(AlN, GaN) have found a wide application at micro and optoelectronics. The
properties of AlN and AlGaN high-temperature (HT) films growths on sapphire
substrates by means of ammonia MBE were studied at this paper. Reflective
high energy electron diffraction (RHEED), atomic-force microscopy (AFM),
transmission electron microscopy (TEM) and X-Ray diffraction were used to study
the properties of epitaxial films. It was found that density of hillocks in HT
AlN layers on sapphire can be reduced from 3x109 down to 2x107
per cm2 through the rise of the ammonia flux during growth process.
It was shown that deposition of AlGaN films under high Ga desorption led to
selective enhancement of lateral growth component at the areas of developed
surface morphology. Enhanced lateral growth allowed to achieve accelerated
transition to 2-D growth mode at the initial stages of growth and led to
formation of stepped surface with terrace width of 1 micron. Also formation of
threading pores was completely suppressed. On the basis of terrace-step-kink
model (TSK model) the mechanism of lateral growth enhancement was suggested.
ammonia MBE, high electron
mobility transistors, AlN, AlGaN, enhanced lateral growth.