Annealing Ag on GaAs: Interplay between cluster formation and Fermi level unpinning

Journal Article · Sat Jul 01 00:00:00 EDT 1989 · J. Vac. Sci. Technol., B; (United States)

DOI:https://doi.org/10.1116/1.584587· OSTI ID:6010960

Chiang, T T; Wahi, A K; Lindau, I; Spicer, W E

It has been shown that upon annealing a 2-monolayer coverage of Ag on UHV-cleaved GaAs at 500 /degree/C, the Ag clusters into islands and the surface Fermi level moves back to within 0.2 eV of the bulk position. In this study, this Fermi level unpinning behavior has been investigated further by using various substrate doping levels and varying the anneal temperature. The Ag clustering process was observed using both ultraviolet photoelectron spectroscopy (UPS) and scanning electron microscopy. Through UPS, the surface Fermi level (/ital E//sub fs/) movement was monitored simultaneously with the clustering process. No distinct temperature for the onset of clustering is observed. Rather, the clustering process occurs continuously over the range of temperatures studied (room temperature to 500 /degree/C), with the Ag clusters growing and increasing in separation as anneals are performed at successively higher temperatures. A 10 min annealing time was sufficient to achieve a stable, equilibrium configuration at each annealing temperature. Movement of the /ital E//sub fs/ back to near the bulk position occurred between 375--450 /degree/C for high doped /ital n/-GaAs (6/times/10/sup 18//cm/sup 3/); whereas no movement of the /ital E//sub fs/ was observed for low doped /ital n/-GaAs (4/times/10/sup 16//cm/sup 3/) up to 475 /degree/C. Similar results were obtained when the experiment was repeated for high doped /ital p/-GaAs (1.4/times/10/sup 19//cm/sup 3/) and low doped /ital p/-GaAs (5/times/10/sup 16//cm/sup 3/). The absence of movement of /ital E//sub fs/ in the low doped GaAs is attributed to the longer substrate depletion length, implying that only the areas beneath and within the depletion length of the Ag clusters are pinned.

• Research Organization: Stanford Electronics Laboratories, Stanford University, Stanford, California, 94305(US)
• OSTI ID: 6010960
• Journal Information: J. Vac. Sci. Technol., B; (United States), Vol. 7:4
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
GALLIUM ARSENIDES
SURFACE PROPERTIES
SILVER
ANNEALING
FERMI LEVEL
HIGH TEMPERATURE
LAYERS
MEDIUM TEMPERATURE
PHOTOELECTRON SPECTROSCOPY
SCHOTTKY BARRIER DIODES
ARSENIC COMPOUNDS
ARSENIDES
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY LEVELS
GALLIUM COMPOUNDS
HEAT TREATMENTS
METALS
PNICTIDES
SEMICONDUCTOR DEVICES
SEMICONDUCTOR DIODES
SPECTROSCOPY
TRANSITION ELEMENTS
360602* - Other Materials- Structure & Phase Studies
360603 - Materials- Properties