Annealing Ag on GaAs: Interplay between cluster formation and Fermi level unpinning
作者:
T. T. Chiang,
A. K. Wahi,
I. Lindau,
W. E. Spicer,
期刊:
Journal of Vacuum Science&Technology B: Microelectronics Processing and Phenomena
(AIP Available online 1989)
卷期:
Volume 7,
issue 4
页码: 958-963
ISSN:0734-211X
年代: 1989
DOI:10.1116/1.584587
出版商: American Vacuum Society
关键词: SILVER;LAYERS;GALLIUM ARSENIDES;SURFACE PROPERTIES;ANNEALING;HIGH TEMPERATURE;FERMI LEVEL;SCHOTTKY BARRIER DIODES;MEDIUM TEMPERATURE;PHOTOELECTRON SPECTROSCOPY;GaAs;Ag
数据来源: AIP
摘要:
It has been shown that upon annealing a 2‐monolayer coverage of Ag on UHV‐cleaved GaAs at 500 °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 (Efs) 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 °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 theEfsback to near the bulk position occurred between 375–450 °C for high dopedn‐GaAs (6×1018/cm3); whereas no movement of theEfswas observed for low dopedn‐GaAs (4×1016/cm3) up to 475 °C. Similar results were obtained when the experiment was repeated for high dopedp‐GaAs (1.4×1019/cm3) and low dopedp‐GaAs (5×1016/cm3). The absence of movement ofEfsin 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.
点击下载:
PDF
(489KB)
返 回