Auger recombination in long-wavelength infrared InNxSb1−x alloys

Abstract

Dilute nitrogen alloys of InSb exhibit strong band gap bowing with increasing nitrogen composition, shifting the absorption edge to longer wavelengths. The conduction band dispersion also has an enhanced nonparabolicity, which suppresses Auger recombination. We have measured Auger lifetimes in alloys with 11 and 15 m absorption edges using a time-resolved pump-probe technique. We find the lifetimes to be longer at room temperature than equivalent band gap Hg 1Ϫy Cd y Te alloys at the same quasi-Fermi level separation. The results are explained using a modified k"p Hamiltonian which explicitly includes interactions between the conduction band and a higher lying nitrogen-related resonant band. © 2001 American Institute of Physics. ͓DOI: 10.1063/1.1355301͔When a small fraction of anion atoms are replaced by nitrogen in GaInAlAs the band gap initially decreases rapidly, by between 0.05 and 0.2 eV at 1% N. [1][2][3][4] This opens the possibility of long wavelength applications in dilute nitride alloys. Despite the decrease in band gap, the conduction band ͑cb͒ edge effective mass has been observed to rise with increasing N content, 5,6 contrary to the prediction of usual k"p theory. The strong band gap bowing and increase in effective mass arise because of a repulsive interaction between the conduction band edge and a higher lying band of nitrogen resonant states. [7][8][9] The band structure of InN x Sb 1Ϫx can be predicted using a modified k"p Hamiltonian previously developed for GaN x As 1Ϫx . 7,8 In this model, the Hamiltonian describing the interaction between the cb edge and nitrogen resonant level is given by ͑1͒The parameters ␣, ␤, ␥, and the energy of the nitrogen resonant level, E N , can be found by analyzing the results of a tight binding model we have developed. 9 In the case of InN x Sb 1Ϫx , the cb energy E C ϭ0.177 eV (ϵ7 m), and we calculate E N ϭ0.647 eV, ␣ϭ␥ϭ0.77 eV, and ␤ϭ2.2 eV. The band gap is therefore predicted to decrease to 110 meV at 1% N, a fractional change of almost 40%. This clearly offers significant potential for long wavelength emission. III-V materials may be made with band gaps smaller than hitherto possible, opening up a longer wavelength region for direct interband transitions.Auger recombination ͑see Fig. 1͒ is the main recombination scattering process in intrinsic and n-type Kane band structure materials with band gap less than about 1 eV and, hence, is the primary factor limiting the maximum operating temperature of emitter and detector devices in this energy range. The Auger lifetime varies as

Band anticrossing in dilute InNxSb1−x

“…We note that it is the effective mass at energies comparable with E g above the cb edge which is important in Auger recombination. The heavier this mass, the slower the Auger rate, and this is consistent with our earlier measurement 10 of increased recombination times in these materials.…”

Band structure of highly mismatched semiconductor alloys: Coherent potential approximation

“…A band gap reduction of more than 180 meV has been observed in GaAs 1-x N x alloys with only 1% N [3]. Similar effects were observed in GaP 1-x N x [4], InP 1-x N x [5], GaSb y As 1-x-y N x [6] and InSb 1-x N x [7] alloys. The large band gap bowing and the lower-than-usual band gap pressure dependence have been found also in group II-VI HMAs such as ZnTe 1-x S x and ZnTe 1-x Se x [8], where electronegative S or Se substitute metallic Te atoms.…”

Narrow band gap group III-nitride alloys

“…Signiÿcant, N-induced band gap reductions have been also reported in other group IIIN x V 1−x materials (see, for example, Ref. [7]) including narrow gap InN x Sb 1−x alloys [8]. The group IIIN x V 1−x materials belong to a much broader class of highly mismatched alloys (HMA) in which metallic (electronegative) atoms are partially replaced by more electronegative (metallic) atoms [9].…”