Diffusion and Electrical Properties of Sulfur Implanted in Gallium-Arsenide

The diffusion and electrical properties of implanted sulfur in GaAs have been investigated with secondary ion mass spectrometry (SIMS) and differential resistivity and Hall measurements. Low dose (7 x 10('12) cm('-2), 250 keV) S implants exhibit redistribution behavior upon annealing which approximates gaussian diffusion. Diffusion coefficients estimated from the tails of annealed profiles are high: 9 x 10('-13) cm('2)/sec, 1 x 10('-12) cm('2)/sec and 8 x 10('-12) cm('2)/sec for 700(DEGREES)C, 800(DEGREES)C and 900(DEGREES)C respectively. The mechanism is believed to be due to defect enhanced diffusion, since these values considerably exceed those reported for S indiffusion into crystalline GaAs. Increasing the implantation dose decreases the diffusivity of S around the peak of the profile, but penetrating tails are still formed. For electrical measurements, type conversion of the Cr-doped substrates used in this study limits the annealing temperature to 800(DEGREES)C. At this temperature, the electrical activation is at best fair for the low (7 x 10('12) cm('-2), 250 keV) and medium (7 x 10('13) cm('-2), 250 keV) doses, being 26% and 36% respectively. Overall activation efficiency is low (2.3%) for high dose (10('15) cm('-2), 250 keV) implants, and although the SIMS profiles reveal little diffusion and a very high S concentration around the original as-implanted peak, almost all of the S in this region is electrically inactive.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Chan, Siu Sing

• Engineering, Electronics and Electrical

Identifier

(UMI)AAI8409886

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/69272