Pump-probe surface photovoltage spectroscopy measurements on semiconductor epitaxial layers

Abstract

Pump-probe Surface Photovoltage Spectroscopy (SPS) measurements are performed on semiconductor epitaxial layers. Here, an additional sub-bandgap cw pump laser beam is used in a conventional chopped light geometry SPS setup under the pump-probe configuration. The main role of pump laser beam is to saturate the sub-bandgap localized states whose contribution otherwise swamp the information related to the bandgap of material. It also affects the magnitude of Dember voltage in case of semi-insulating (SI) semiconductor substrates. Pump-probe SPS technique enables an accurate determination of the bandgap of semiconductor epitaxial layers even under the strong influence of localized sub-bandgap states. The pump beam is found to be very effective in suppressing the effect of surface/interface and bulk trap states. The overall magnitude of SPV signal is decided by the dependence of charge separation mechanisms on the intensity of the pump beam. On the contrary, an above bandgap cw pump laser can be used to distinguish the signatures of sub-bandgap states by suppressing the band edge related feature. Usefulness of the pump-probe SPS technique is established by unambiguously determining the bandgap of p-GaAs epitaxial layers grown on SI-GaAs substrates, SI-InP wafers, and p-GaN epilayers grown on Sapphire substrates.

Imaging photoinduced surface potentials on hybrid perovskites by real-time Scanning Electron Microscopy

“…Extended review papers on photovoltage phenomena and related characterizations "at the crossroads of physics, chemistry and electrical engineering" have been provided e.g by Shapira, 2001, 1999). Among commonly used experimental methods to evaluate the effect we can mention photo-assisted Kelvin probe spectroscopy (Ali Deeb et al, 2017), all-optical pump-probe absorption spectroscopies (Jana et al, 2014) and photoemission electron spectroscopies (Tanaka, 2012).…”

Ultranarrow Band UV Detection in GaN with Simple Device Architecture

“…[ 22 ] An additional 1064 or 325 nm CW laser (pump beam) is used along with the conventional SPS setup for pump‐probe SPS (pp‐SPS) measurements. [ 23 ] Temperature‐dependent measurements are also performed in the temperature range of 10–425 K where for low‐temperature measurements, the sample is placed in a closed‐cycle helium cryostat. For spectral response and transient photoresponse measurements, a Keithley 2450 source meter is used along with a Xenon lamp and iHR 320 monochromator assembly as the illumination source.…”

Pump–probe micro-spectroscopy and 2D materials

“…By using numerical simulations methods, the photo associative creation of translationally ultra-cold rubidium molecules are expressed. Pumpprobe surface photovoltage spectroscopy (SPS) analysis is carried out on semiconductor epitaxial layers [83]. TMDCs, graphene, silicon nano wires, black phosphorus, perovskite materials and heterostructure's have made an exceptional class detail.…”