Probing charge carrier compensation in high energy ion irradiated III–V semiconductor by Raman spectroscopy and Hall measurements

Abstract

Raman spectroscopy and Hall measurements have been carried out to investigate the differences in near‐surface charge carrier modulation in high energy (~100 MeV) silicon ion (Si8+) and oxygen ion (O7+) irradiated n‐GaAs. In the case of O ion irradiation, the observed decrease in carrier concentration with increase in ion fluence could be explained in the view of charge compensation by possible point defect trap centers, which can form because of elastic collisions of high energy ions with the target nuclei. In Si irradiated n‐GaAs one would expect the carrier compensation to occur at a fluence of 2.5 × 1013 ions/cm2, if the same mechanism of acceptor state formation, as in case of O irradiation, is considered. However, we observe the charge compensation in this system at a fluence of 5 × 1012 ions/cm2. We discuss the role of the complex defect states, which are formed because of the interaction of the primary point defects, in determining carrier concentration in a Si irradiated n‐GaAs wafer. The above results are combined with the reported data from the literature for high energy silver ion irradiated n‐GaAs, in order to illustrate the effect of both electronic and nuclear energy loss on trap creation and charge compensation. Copyright © 2016 John Wiley & Sons, Ltd.

Experimental re-evaluation of proton penetration ranges in GaAs and InGaP

“…The observation of an increase in the phonon intensity is opposite to the expected degradation of the crystalline quality that would result in a peak flattening with intensity reduction and width increase [22]. An increment of the phonon intensity in irradiated regions has been already observed in doped materials, and usually associated to electron density compensation [8,9]. One of the consequences of density compensation, is that the LO phonon frequency changes remarkably due to changes in the electron-phonon coupling [23].…”

“…Solar cells for space applications are multijunctions mainly based on InGaP, GaAs and Ge, but also AlGaAs and AlInP among others III-V semiconductors are eventually present. However, most of the radiation damage studies were performed on the well known material GaAs: determination of proton and helium ranges [6], irradiation induced changes of refractive index [7], carrier compensation [8,9], and annealing effects [10], to give some examples. The other III-V compounds were only laterally investigated, even if they are constituents of many kinds of devices for space applications and these studies were usually directly related to the devices performance [11,12].…”

“…Raman spectroscopy allows to study the crystal changes as the phonon spectra show to be sensitive to amorphisation of the crystal and electron density changes induced by radiation. Previous works in GaAs [9] and InGaP [16] have shown that defects created during irradiation act as traps for free carriers, resulting in carrier density compensation, thus in changes in the phonon intensities. In this work we intentionally investigate undoped samples, and demonstrate that increases in the phonon intensities must be also related to changes in the optical properties of the material, like absorption and emission rates, and not only, as always assumed, related to density compensation via electron-phonon coupling.…”

Recent advances in linear and non‐linear Raman spectroscopy. Part XI

“…Mishra and co‐workers probed charge carrier compensation in high energy ion irradiated III‐V semiconductor by Raman spectroscopy and Hall measurements. Their results are combined with the reported data from the literature for high energy silver ion irradiated n‐GaAs, in order to illustrate the effect of both electronic and nuclear energy loss on trap creation and charge compensation . Oreshonkov et al measured the Raman spectra and phase composition of MnGeO 3 crystals.…”