Superlinear increase of photoluminescence with excitation intensity in Zn-doped GaN

Abstract

Follow this and additional works at: http://scholarscompass.vcu.edu/phys_pubs Part of the Physics Commons Reshchikov, M.A., Olsen, A.J., Bishop, M.F., et al. Superlinear increase of photoluminescence with excitation intensity in Zn-doped GaN. Physical Review B, 88, 075204 (2013).We have observed a superlinear increase of photoluminescence (PL) intensity in a narrow range of excitation intensities for Zn-doped GaN. The characteristic intensity at which the abrupt increase occurs increases with increasing temperature. This is unlike the usual observations for defects in semiconductors in which the PL intensity increases linearly with excitation intensity, saturating at high intensity because defects become saturated with photogenerated charge carriers. The observed phenomenon is attributed to a redirection of electron and hole flow from nonradiative centers at low excitation intensity to a recombination path via the Zn Ga acceptor at high excitation intensity. This is the same explanation responsible for the abrupt thermal quenching of PL reported earlier [Reshchikov et al., Phys. Rev. B 84, 075212 (2011).]

Comparative study ofab initiononradiative recombination rate calculations under different formalisms

“…In this 1D model, the atomic degree of freedom is represented by a single generalized configuration coordination Q. They also calculated the carrier capture rate of GaN:Zn Ga -V N , and found their result (at room-temperature)as -8 1.0 10 × cm 3 /s, which is higher than our previous result 3 10 × cm 3 /s [18]. In their discussion, they argued for the use of static coupling theory instead of adiabatic formalism.…”

“…In our previous paper [10], we calculated the nonradiative recombination capture coefficients of GaN:Zn Ga -V N using adiabatic formulation, the result is [18]. We note that, for this system, the Marcus theory and quantum CT theory yield an order of magnitude too small capture coefficients as shown in Table.II.…”

“…Despite the fact that the ab initio calculated electron-phonon coupling constants and all the phonon modes are used in the formalism, the calculated rate is several orders of magnitude too small, especially compared to the newly measured experimental data [18] which appeared after Ref. [10].…”

“…We will also calculate GaN:Zn Ga -V N complex. Not only it has been studied before in our previous work [10], there are also recent new experiments [18] which make the experimental results more certain.…”

Abrupt and tunable quenching of photoluminescence in ZnO

“…Finally, at P exc 4 3 Â 10 À 2 W/cm 2 , the exciton PL efficiency approaches a plateau, while the OL quantum efficiency decreases due to saturation of the related defects with photogenerated holes. The rise of the PL quantum efficiency, observed for both PL bands between 10 À 3 and 3 Â 10 À 2 W/cm 2 can be explained within the model of abrupt and tunable quenching of defectrelated PL [32]. …”