Picosecond carrier lifetime in GaAs implanted with high doses of As ions: An alternative material to low-temperature GaAs for optoelectronic applications

Abstract

Nonstoichiometric GaAs obtained by implantation with 2 MeV arsenic ions at 1015 cm−2 dose is studied. As-implanted samples show a <200 fs lifetime of photocarriers and low resistivity due to hopping, with mobility less than 1 cm2/V s. Annealing of the samples at 600 °C leads to substantial recovery of postimplant damage, as seen from Rutherford backscattering channeling spectra and mobility increase to about 2000 cm2/V s, but photocarrier lifetime is still about 1 ps. These parameters are similar to those of low-temperature GaAs annealed at 600 °C, and make arsenic implanted GaAs an interesting material for optoelectronic applications.

Material and ultrafast optoelectronic properties of furnace-annealed arsenic-ion-implanted GaAs

“…The structural and electrical characteristics of LT-GaAs and GaAs : As have been shown to be quite similar [8], [9]. The ultrafast optical characteristics of the as-implanted arsenic-rich GaAs materials have been reported [10]- [12]. Subpicosecond carrier lifetimes were observed.…”

“…However, as-implanted or as-grown nonstoichiometric GaAs obtained by using either the arsenic-ion-implantation or the LTMBE process suffer from the following: the crystallinity of the material is degraded [13], [14]. As a result, the carrier mobility is substantially lower [12], [15]. This also leads to a defect-dominated hopping conducting mechanism, which destroys the highly resistive nature of the original substrate [8], [15].…”

Semiconductors for terahertz photonics applications

“…It has been demonstrated later that the carrier recombination characteristics of the As-ion implanted GaAs closely remind those of LTG GaAs. E.g., electron trapping time in GaAs implanted by 2 MeV energy ions was equal to 30 fs before annealing [70] and 1 ps after annealing at the temperature of 600 o C [81]. Spatially resolved carrier lifetime measurements of the As-ion implanted and annealed GaAs [87] have shown that carriers decay faster at the surface, whereas the precipitates are predominantly nucleating deeper in the bulk of the crystal, in the proximity of the ion-stop range.…”

“…Therefore, the presence of excess arsenic, which could be the source of the As Ga related point defects, can be expected at the surface of all samples irradiated with heavy, high-energy ions. Such defects have been detected by electron-paramagnetic-resonance measurements in As-implanted samples [81] and in some of the Ga + -implanted samples [82].…”

“…GaAs implanted with heavy, high energy ions of As was proposed as an alternative material for ultrafast semiconductor components to LTG GaAs in [81,82]. Because the characteristics of both materials are strikingly similar, ion-implanted GaAs could be used as a substrate material for photoconductive antennae or other components operating in the THz frequency range.…”