AVS 46th International Symposium
    Electronic Materials and Processing Division Monday Sessions
       Session EM-MoM

Paper EM-MoM4
Selective Area Growth of GaN on Si by Chemical Beam Epitaxy

Monday, October 25, 1999, 9:20 am, Room 608

Session: Nitride Epitaxy
Presenter: A. Tempez, University of Houston
Authors: E. Kim, University of Houston
A. Tempez, University of Houston
N. Medelci, University of Houston
I.E. Berishev, University of Houston
A. Bensaoula, University of Houston
Correspondent: Click to Email
One possible advantage of high vacuum deposition techniques over MOCVD is the realization of GaN device structures on Si wafers. In the case of MOCVD and sapphire substrates, selective GaN lateral regrowth over SiO@sub 2@ masks has been shown to reduce considerably the defect density in the epilayers. Thus far, very little data is available for regrowth using MBE techniques. In our previous studies of GaN deposition by chemical beam epitaxy (CBE) with TEGa and ammonia precursors, we have shown that no nucleation occurs on a sapphire surface. Using the same CBE precursors, we investigate here the selective nucleation process on Si wafers patterned with various oxide and nitride masks. The selectivity of the nucleation process was monitored in real time using time of flight ion scattering and recoil spectroscopy and RHEED. Two direct recoil spectroscopy (DRS) detectors mounted at 40 and 70° recoil angles are associated with MSRI (mass spectroscopy of recoiled ions) analyzers (sector and reflectron, respectively). These time refocusing analyzers allow for higher resolution and sensitivity than DRS. Our results show that the MSRI Si to O peak intensity ratio during GaN regrowth of SiO@sub 2@ patterned GaN is constant within the condition range we explored. This shows a 100% selective overgrowth process and is confirmed by SEM analysis. Following these experiments, we then implemented various regrowth schemes such as the use of a thin AlN single crystal layer on Si by a reactive MBE method followed by patterning and etching in an Ar-Cl@sub 2@-BCl@sub 3@ RF plasma. In this presentation, we will summarize our observations on the effect of the growth conditions (growth temperature and Ga/N flux ratio) on the selectivity of the nucleation process and will show our most recent data on the optimized regrown GaN layers- including their optical, electrical and field emission properties.