Time-resolved experimental study of carrier lifetime in GaN epilayers

Abstract

Time-resolved photoluminescence and light-induced transient grating measurements of GaN epilayers show that the photoluminescence decay can be described by two coupled exponential terms and that carrier mobility and lifetime in GaN epilayers are correlated within the model which accounts for nonradiative carrier recombination predominantly at dislocations. The obtained results demonstrate that migration-enhanced metalorganic chemical vapor deposition (MEMOCVD™) allows for growth of high-quality GaN epilayers on sapphire substrates with the dislocation density close to 108cm−2, carrier lifetime as long as 2 ns, and ambipolar diffusion coefficient of 2.1cm2s−1 corresponding to the hole mobility of approximately 40cm2V−1s−1.

Low-temperature time-resolved cathodoluminescence study of exciton dynamics involving basal stacking faults in a-plane GaN

“…16 and derived for GaN, 17 we account for the pulsed electron-beam excitation at t = 0 by a Gaussian distribution of free excitons, with half-width of ϳ200 nm, along the c-axis, centered between the two BSFs. These free excitons then diffuse with the ambipolar diffusion coefficient D FX = 4 cm 2 s −1 determined independently 18 and can also recombine radiatively and nonradiatively ͑lifetimes R and NR ͒, or be captured by neutral donors ͑ C ͒ or BSFs. For the latter process, as soon as a free exciton reaches a BSF, we consider it instantaneously captured.…”

Modeling and simulation of bulk gallium nitride power semiconductor devices

“…Hole mobility, on the other hand has been much less explored and most work has been theoretical. [29][30][31]67,[76][77][78][79] Unlike electrons, the hole mobility does not show a negative differential mobility region and tends to saturate at high fields. At low field both electron and hole mobility is given according to the doping and temperature dependent Arora model according to Eq.…”

(-201) β-Gallium oxide substrate for high quality GaN materials

“…Surprisingly, the ratio of PL intensity of the bandedge emission at 6 K to that at 300 K (2.7:1), is significantly lower than that of the commercial GaN/Al 2 O 3 reference sample (20:1), which is similar to the value reported in literature. 15 However, the full width half maximum (FWHM) of the GaN/ Ga 2 O 3 bandedge peak is larger than that measured for the sample grown on Al 2 O 3 . The redshift of the bandedge peak of GaN/Ga 2 O 3 can be due to the slighter compressive strain of the sample compared to that of GaN/Al 2 O 3 .…”

“…Usually, the slow decay of GaN material is affected by the nonradiative recombination near TD. 15,17 As nonrediative recombination occurs due to the carriers trapped near the TD, which results in short lifetime, the shorter decay time of GaN/Ga 2 O 3 is, therefore, due to the higher TDD of this sample compared to the one grown on sapphire. Therefore, we find this result promising, as reducing the dislocation density by optimizing the growth of these samples can result in high optical efficiency GaN materials with significantly longer lifetime.…”