Defect topography on GaAs wafers by microwave‐detected photo‐induced current transient spectroscopy

Abstract

PACS 71.55. Eq, 72.40.+w Photo-generated charge carriers can be detected by microwave absorption. This enables non-destructive measurements of photoconductivity with a spatial resolution depending on the spot size of the light source. In addition, the photoconductivity can be measured as a function of time during light on and off with high time resolution. The resulting photoconductivity transients contain information about defect parameters like conventional methods such as deep level transient spectroscopy or photo-induced current transient spectroscopy, however, with the advantage of high spatial resolution. First results of microwave detected photo-induced current transient spectroscopy measurements on different semi-insulating gallium arsenide samples will be presented.

Contact Free Defect Investigation in as grown Fe-doped SI-InP

“…Moreover, it is shown that the method of microwave detected photoconductivity (MDP), which was successfully applied to investigate the homogeneity of GaAs wafers [10][11][12][13][14][15][16], works as successfully for InP wafers. The nature of the contrast causing defects is not yet known.…”

“…The experimental setup for the microwave detected photocurrent measurements MDP and MD-PICTS was already described elsewhere [10][11][12][13]. Through band-to-band excitation (hν ≥ 1.3eV) excess carriers are generated, which are detected via high sensitivity microwave absorption.…”

“…To clarify these questions, the methods of MD-PICTS and MDP, which proved themselves as very successful for defect investigations of GaAs wafers [10][11][12][13], were applied to Fe-doped InP samples for the first time. The advantage of using MD-PICTS and MDP compared to conventional methods is the possibility to investigate defect characteristics and their distribution in a contact-free, non-destructive way and with high spatial resolution.…”

Explanation of positive and negative PICTS peaks in SI-GaAs

“…Microwave detected photo induced current transient spectroscopy (MD-PICTS) is a well-known tool for the contact-less and non-destructive investigation of electrical properties of defects in semiconductors [1][2][3]. Especially in semi-insulating GaAs (SI-GaAs) positive and negative PICTS peaks, which are mostly attributed to the EL2 defect, can be observed at temperatures above &350 K, whereas the exact peak maximum temperature depends on the details of the applied PICTS data evaluation.…”