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Grain Growth and Mobility in Nanocrystalline Ge Films

Published online by Cambridge University Press:  30 August 2012

Siva Konduri
Affiliation:
Dept. of Electrical and Computer Engineering, Iowa State University, Ames, IA 50011
Max Noack
Affiliation:
Microelectronic Research Center, Iowa State University, Ames, IA 50011
Vikram Dalal
Affiliation:
Dept. of Electrical and Computer Engineering, Iowa State University, Ames, IA 50011
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Abstract

In this paper, we report on deposition and properties of nanocrystalline Ge:H films . The films were grown from germane and hydrogen mixtures using Radio frequency Plasma-enhanced chemical vapor deposition (RF-PECVD) process using ∼45 MHz frequency. The crystallinity of the films was measured using Raman measurements and from x-ray diffraction techniques, it was found that the grain size was a strong function of deposition pressure, temperature and hydrogen/germane ratios. High hydrogen ratios and high powers led to films with smaller grains. Higher pressures and smaller hydrogen/germane ratio led to films with larger grain sizes, as did higher growth temperatures. The mobility of electrons and holes was measured using space charge limited current (SCLC) techniques in n+-n-n+ devices. It was found that nominally undoped films were generally n type with carrier concentrations in the 1E14/cm3 range. Mobility was found to increase with grain size, with 60 nm grains showing mobility in the 2-3 cm2/V-s range.

Type
Articles
Copyright
Copyright © Materials Research Society 2012

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References

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