Low Temperature Photoluminescence Studies of Narrow Bandgap Gaassbn Quantum Wells on GaAs
- PDF / 243,564 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 23 Downloads / 192 Views
M10.3.1
LOW TEMPERATURE PHOTOLUMINESCENCE STUDIES OF NARROW BANDGAP GaAsSbN QUANTUM WELLS ON GaAs K.E. Waldrip, E.D. Jones, N.A. Modine, F. Jalali, J.F. Klem, and G.M. Peake Sandia National Laboratories Albuquerque, NM 87185
We present low-temperature (T = 4K) photoluminescence studies of the effect of adding nitrogen to 6-nm-wide single-strained GaAsSb quantum wells on GaAs. The samples were grown by both MBE and MOCVD techniques.The nominal Sb concentration is about 30%. Adding about 1 to 2% N drastically reduced the bandgap energies from 1 to 0.75 eV, or 1.20 to 1.64 µm. Upon performing ex situ rapid thermal anneals, 825ºC for 10s, the band gap energies as well as the photoluminescence intensities increased. The intensities increased by an order of magnitude for the annealed samples and the band gap energies increased by about 50 - 100 meV, depending on growth temperatures. The photoluminescence linewidths tended to decrease upon annealing. Preliminary results of a first-principles band structure calculation for the GaAsSbN system are also presented. INTRODUCTION The requirement for optoelectronic devices operating at room temperature between 1.3 and 1.55 µm on GaAs is well documented. [1] In the past few years, the quaternary alloy system, InGaAsN has been the principle candidate material for long wavelength laser systems. [1] Because of the versatility gained by using GaAs substrates for InGaAsN alloys, there have been many studies showing InGaAsN lasers with low threshold current densities, CW laser operation, and large T0 in the 1.1 to 1.3 µm wavelength regions. [1-3] These InGaAsN studies have led to several important conclusions regarding the incorporation of nitrogen into the III-V zincblende materials such as GaAs. Because of possible N segregation and other growth issues, it appears that relying on nitrogen to be the principle method for reducing the band gap energy to the 1.55 µm wavelength region is impractical. In fact, low N concentrations (~ 1%) appear to be preferred. The InGaAsN/GaAs alloy system has proven to be highly successful for producing GaAs-based 1.3 µm lasers. However, in addition to N segregation issues, increasing the In concentration increases the lattice-mismatch strain and because of critical layer thickness considerations, decreased quantum well widths (and hence decreased laser gain) are necessary to to be able to extend the wavelengths out to 1.55 µm. To date, reliable operation of InGaAsN/GaAs devices with wavelengths longer than 1.3 µm has, proven to be difficult. The GaAsSb alloy system has also been recognized and studied as a viable alternative to InGaAsN for realizing long wavelength laser operation. In many ways, GaAsSb compliments the InGaAs studies mentioned above. Strained quantum wells of GaAsSb/GaAs produce lasers in the 1.2 µm wavelength range. [2-3] Thus a natural extension of the ideas for reducing band gap energy is to add N to GaAsSb. In this paper, we report preliminary results of adding N to single-strained 6-nm-wide GaAsSb quantum wells using low-temperature
Data Loading...
