MIT Department of Electrical Engineering & Computer Science

SPECIAL SEMINAR

Resonant Tunneling through Zero-Dimensional Si Impurity States in GaAs/AlAs Single Barrier Structures

Hiroyuki Fukuyama
NTT LSI Laboratories, Atsugi, Japan

(about 20 minutes)

Abstract

Tunneling current through a Si-planar-doped AlAs barrier is studied, showing excess current through this single barrier, which is not observed when the barrier is undoped. The dI/dV--V characteristics indicate that the excess current is due to resonant tunneling through the zero-dimensional Si impurity states formed in the AlAs barrier. The impurity states are probably related to the X valley in the AlAs barrier.

Effects of Annealing using Plasma-CVD SiN Film as a Cap on 2DEG Mobility

Shunji Nakata
NTT LSI Laboratories, Atsugi, Japan
(about 20 minutes)

Abstract

We show how the carrier density and mobility of 2DEG are influenced by fabrication processes using SiN films as masks for etching and also as masks for subsequent MOCVD regrowth for burying quantum wires. Annealing

with P-CVD SiN film as a cap, which is the simulated process for regrowth, results in a large decrease in the carrier density and mobility of 2DEG. However, both are restored by reannealing after removing the SiN film from the wafer. It is shown that the increase of the defect density by annealing using P-CVD SiN film is related to the strong compressive stress of the film.

Monday, September 26, 1994 from 10:30 - Noon

Room 36-428 (RLE Conference Room)