UV-light amplification (absorption) in group III-nitride heterostructures
Liubov E.Lokot, V.A.Kochelap, V.I.Sheka
Institute of Semiconductor Physics,
National Academy of Sciences of Ukraine, Kyiv, Ukraine
Recently, wurtzite strained quantum wells (QWs) have received considerable attention in view of aplications in light-emitting diodes, laser diodes, and photodetectors in the blue and ultraviolet wavelengths
diapason [1-3]. We have analyzed a wurtzite GaN/Al0.3Ga0.7N strained QW with well width 26A at room temperature.
When a single layer of GaN material is grown between two Al0.3Ga0.7N layers, which are characterized by wider bandgaps, than the central layer forms a QW for both electrons and holes [4,5].
The valence band states are described by using the Rashba-Sheka-Pikus Hamiltinian [6-8]. In our calculations the Hamiltonian is taken in a block-diagonalized form [9,10].
We have found the hole spectra, the interband momentum-matrix element and the light amplification spectra for strained wurtzite QW lasers.
Our calculations of the light amplification coefficient are shown in Fig.1 for an GaN/Al0.3Ga0.7N QW for different injected electron-hole plasma concentrations and at the temperature T=300K. This heterostructure supports the light amplification in the ultraviolet spectral range from 3.747 eV (l=3301A) to 3.860 eV (l=3205A). The light amplification curves, which are collected in Fig.1, show threshold character of the population inversion. The threshold concentration is 4*1012cm-2. The maximum values of the light amplification is centered near the photon energy corresponding to
3.772 eV (l=3279A).
In accordance with the criterion for the light amplification for interband phototransitions , at a finite temperature there is a threshold value of the carrier concentration of about 4*1012cm-2 . Below this value there is no amplification.
For particular carrier concentration 1013cm-2 the width of the spectral ragion of the light amplification is 110 meV.
In conclusion, we have found spectral, concentration and temperature dependences of the light amplification of UV-light in group III-nitride heterostructures.
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