The study of the nucleation layer defects influence on leakage in heterostructures for high electron mobility transistors
Andreev 1, Yu. V. Grishchenko 1, I. S. Ezubchenko 1,
M. L. Zanaveskin 1, I. O. Mayboroda 1, M. A. Rudik 1,
Yu. V. Fedorov 2
National research centre "Kurchatov institute"
Institute of UHF Semiconductor Electronics of RAS
The paper is received on December 24, 2014
Abstract. The issue
of improving the morphology relief of the nucleation layers of the nitride
heterostructure on sapphire substrates grown by ammonia
MBE, for high electron mobility
transistors (HEMT), was investigated. It was found that during deposition of
high temperature layer of AlGaN unlike AlN, gallium can act as autosurfactant ,
promoting to establishment
of the two-dimensional growth
mode. It was shown that use of nucleation layer with improved morphology of the
surface can reduce leakage currents on several orders of magnitude in
heterostructure for HEMT. On the basis of heterostructure
with minimal leakage currents, the
test transistors with
a gate length LG = 0,15 µm,
showing Ft up to 71 GHz and
to 172 GHz, which is close to the results obtained in the heterostructures grown by chemical vapor deposition (MOCVD), were produced.
Key words: ammonia MBE, high electron mobility transistors, GaN, AlGaN, nucleation layers.