Luminescence decay in highly excited GaN grown by hydride vapor-phase epitaxy

Abstract

Carrier recombination dynamics in GaN grown by hydride vapor-phase epitaxy has been studied by means of transient photoluminescence under high photoexcitation conditions that are close to stimulated emission regime. The luminescence transient featured an exponential decay with the time constant of 205 ps at room temperature. The transient was shown to be in good agreement with a model of saturated centers of nonradiative recombination with the trap density of ∼1017 cm−3 and carrier recombination coefficients of ∼10−8 cm3/s. In such a regime, the lifetimes of electrons and holes have a common value of 410 ps.

Comparative study ofab initiononradiative recombination rate calculations under different formalisms

“…Normally nonradiative transitions reduce device efficiencies by reducing photo generated carriers, suppressing luminescence, reducing carrier lifetimes, or enhancing defect diffusion during device operations [4]. Since the direct measurement of such processes is often difficult [5][6][7], especially to identify the responsible defects, it is very desirable to use ab initio calculations to study the related phenomena. However, so far, there is a lack of commonly accepted way to calculate the SRH, which is the focus of the current study: to compare different approaches to establish the correct ab initio procedure.…”

Transients of Carrier Recombination and Diffusion in Highly Excited GaN Studied by Photoluminescence and Four-Wave Mixing Techniques

“…1b) decays almost exponentially with a characteristic time constant τ LU = 275 ps. The created EHP density of 10 19 cm −3 is sufficient to maintain the deep-trap saturation regime [3]. The estimated electron capture time, τ e = 2τ LU = 550 ps, is typical of heteroepitaxialy grown good-quality samples [2].…”

“…Carrier lifetime, which can be extracted from time-resolved measurements, is one of the crucial indicators of the materials quality [2,3]. However, it reflects a complex average over all the processes, which diminish the carrier density: spontaneous and stimulated band-to-band recombination of nonthermalized electron-hole plasma, capture of free carriers to radiative and nonradiative traps, carrier diffusion, etc.…”

Photoluminescence and Photoconductivity Dynamics in Semi-Insulating Epitaxial GaN Layers

“…1a). The Y-band PL disappears because of saturation of traps and nonlinear redistribution of the carrier capture flows with an increase in excess carrier density [6]. The UV band exhibits intense constituents of both stimulated and spontaneous emission, while an increase in intensity of the B-band PL band is smaller when compared with the UV band.…”