Theoretical prediction of GaN lasing and temperature sensitivity

Abstract

We present a theoretical prediction of the threshold current density and the temperature sensitivity of a GaN laser operating in the intrinsic band-to-band transition. We calculate the material gain and spontaneous emission spectrum for unintentionally doped bulk GaN under carrier injection. All stimulated and spontaneous emission calculations are compared to those of bulk GaAs. The transparency carrier density of GaN is found to be more than four times that of GaAs, and the momentum matrix element for optical transitions in bulk GaN is estimated to be about one-third the value in GaAs. In addition, the differential gain is approximately four times smaller in GaN. These differences are attributed to the larger effective masses of the electrons and holes in GaN. The calculated characteristic temperature T0 of the threshold current density for a GaN laser ranges from 185 to 220 K, which agrees well with the recently observed data from optical pumping experiments.

Free-carrier screening of polarization fields in wurtzite GaN/InGaN laser structures

“…This is of interest since it has been shown that the sheet density necessary to achieve lasing in InGaN/ GaN laser structures is unusually large for typical semiconductor lasers. 2,5,6 The well width is also an important parameter in these structures since the total potential drop across the structure is directly proportional to the product of polarization field and well width, if free-carrier screening is neglected. Indeed, as mentioned earlier, it has been argued that structures with well width above than 50 Å should not be able to produce laser action.…”

Electronic and Optical Properties of Bulk GaN and GaN/AlGaN Quantum Well Structures

“…On the other hand, it is expected that ZB nitrides might have special advantages to the LD operation. Although there have been a few studies on ZB GaN LDs [9,10,11], the comprehensive study, taking the detail electronic structure into account and comparing it with WZ GaN LDs, has not been reported yet. Thus, it is very important to clarify the relation between the LD performance and the crystal symmetry in III-V nitrides.…”

Effect of uniaxial stress on photoluminescence in GaN and stimulated emission inInxGa1−xNIchimiya1, Watanabe2, Ohata3 et al. 2003Phys. Rev. B9050View full textAdd to dashboardCite

“…4 -9 However, it has been pointed out that high carrier density is required to generate the optical gain compared with the GaAs family. 10,11 This is due to the large effective masses in both conduction and valence bands of GaN; the strong electron affinity and the weak spin-orbit coupling of nitrogen atoms yield large electron and hole effective masses. The high density of states due to the heavy masses requires high carrier density to achieve the population inversion.…”