Effects of Ultrasonic Cleaning on Carrier Lifetimes and Photovoltage in Monocrystalline Silicon

Abstract:

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Effects of a kHz-frequency ultrasonic cleaning of silicon wafers on free carrier lifetimes and the photovoltage magnitude are addressed. It is found that the initial photovoltage decay, taken before ultrasonic treatments, can be fitted to a double-exponent form, exhibiting the involvement of shorter- and longer time recombination and trapping centers. The decay speeds up remarkably due to the treatment, and the rapid component of the decay grows at the expense of the slow component. It is also found that, before the treatment, the decay time is markedly non-uniform over the wafer surface, implying the existence of distributed sites affecting carrier lifetimes. The cleaning causes an overall smoothening of the lifetime distribution, which is accompanied by the above shortening. A likely explanation of the effects is based on two facts: (i) the cavitating bubbles are capable of locally removing the surface oxide layer affecting the dangling bonds on the bare Si surface, and (ii) the oxygen and hydrogen, decomposed in water at elevated pressures and temperatures occurring inside a cavitating bubble, can micro-precipitate the Si wafer thus affecting the recombination rate.

Info:

Periodical:

Solid State Phenomena (Volumes 178-179)

Edited by:

W. Jantsch and F. Schäffler

Pages:

221-225

DOI:

10.4028/www.scientific.net/SSP.178-179.221

Citation:

A.B. Nadtochiy et al., "Effects of Ultrasonic Cleaning on Carrier Lifetimes and Photovoltage in Monocrystalline Silicon", Solid State Phenomena, Vols. 178-179, pp. 221-225, 2011

Online since:

August 2011

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Price:

$35.00

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