Carrier Recombination Processes in GaAs Wafers Passivated by Wet Nitridation

Abstract

As one of the successful approaches to GaAs surface passivation, wet-chemical nitridation is applied here to relate the effect of surface passivation to carrier recombination processes in bulk GaAs. By combining time-resolved photoluminescence and optical pump—THz probe measurements, we found that surface hole trapping dominates the decay of photoluminescence, while photoconductivity dynamics is limited by surface electron trapping. Compared to untreated sample dynamics, the optimized nitridation reduces hole- and electron-trapping rate by at least 2.6 and 3 times, respectively. Our results indicate that under ambient conditions, recovery of the fast hole trapping due to the oxide regrowth at the deoxidized GaAs surface takes tens of hours, while it is effectively inhibited by surface nitridation. Our study demonstrates that surface nitridation stabilizes the GaAs surface via reduction of both electron- and hole-trapping rates, which results in chemical and electronical passivation of the bulk GaAs surface.

Comparison of Triethylgallium and Trimethylgallium Precursors for GaInP Nanowire Growth

“…This type of power dependence was previously associated with the filling of trap states under high fluence, leading to a longer average lifetime of the excited carriers. [ 46,51,52 ] In accordance with the model presented for Ga x In 1– x P NWs in the study by Zhang et al, [ 46 ] we assign this observation to the filling of shallow trap states that coexist with the deep level traps mentioned earlier. Plotting the 1 / e lifetimes as a function of excitation intensity supports the interpretation of coexisting deep and shallow trap states, particularly for the NW arrays grown by the use of TEGa (see Figure S4, Supporting Information).…”

An Insight into the Excitation States of Small Molecular Semiconductor Y6

“…PLQY and TRPL were measured in the setups described in [ 44 , 45 ] at Chemical Physics, Lund University. The PL quantum yield system includes continuous wavelength (CW) laser sources, a spectrometer (AvaSpec-ULS2048-USB2-UA-50), and an integrating sphere (HORIBA, Quanta-φ, F3029), which have been specially designed to measure the absolute PLQY of solution and solid samples.…”

“…For PLQY measurement of the Y6 film, the sample was put at the mount at the bottom of the integrating sphere, and was excited by a 780 nm CW laser with an excitation fluency of ~5 mW/cm 2 . TRPL was measured in a setup described in [ 44 , 46 ]. A Ti:sapphire fs laser (Spectra-Physics, Mountain View, CA, USA, Tsunami, 81 MHz) at 775 nm was used as an excitation source with a pulse duration of 100 fs.…”

Ground- and excited-state characteristics in photovoltaic polymer N2200

“…2.4 Time-resolved photoluminescence (TRPL) and absolute photoluminescence quantum yield (PLQY) measurements TRPL was measured in a setup described in the previous works. 27,28 A fs pulsed laser (Tsunami, Spectra-Physical) with wavelength of 800 nm, pulse duration of $100 fs and repetitive rate of 80 MHz, was employed as the laser source. The frequency-doubled laser (400 nm) was employed as exciting light.…”