The study of the nucleation layer defects influence on leakage in heterostructures for high electron mobility transistors

 

A. A. 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

 

¹ National research centre "Kurchatov institute"

² 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 L_G = 0,15 µm, showing F_t up to 71 GHz and Fmax up 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.