Optically-Pumped Lasing of Doped ZnSe Epitaxial Layers Grown by Metal-Organic Vapour-Phase Epitaxy

Abstract

Laser action in undoped, nitrogen and chlorine doped ZnSe epitaxial layer has been achieved and investigated at pulse optical excitation by N2 laser radiation with a frequency of 1000 Hz from liquid nitrogen temperature up to near room temperature at 270 K. The highest value of ZnSe laser energy and power were E = 5×10−8 J and P = 5 W at Iexc = 800 kW/cm2. The laser line positions in doped samples ZnSe:Cl λ = 450.7 nm) and ZnSe:N λ = 451.2, 451.5, 452.0 and 455.5 nm at different excitation intensities) are shifted to the high wavelength side compared to undoped ZnSe λ = 449.8 nm). It was shown that doping ZnSe with both acceptor or donor impurities as well as using a ZnMgSSe barrier layer between the ZnSe layer and the substrate is favourable to increase PL efficiency and to decrease the laser threshold. The lowest threshold value (130 to 150 kW/cm2) was achieved in ZnSe:N grown with hydrogen carrier gas. The results obtained from measurements of the laser line positions as well as from the evaluation of the nonequilibrium carrier concentration proves that the ZnSe lasing mechanism under excitation by the N2 laser radiation is the recombination in an EHP. We found that under high excitation intensity a degradation of the excited region of the ZnSe takes place causing a decrease of the emission intensity. Under lower excitation power the PL intensity enhances during the course of irradiation.

High-temperature optically pumped lasing in ZnMgSSe/ZnSe heterostructures grown by metalorganic vapor phase epitaxy

“…After the report of the first II-VI-based junction laser in 1991, 2 a great number of investigations have been devoted to the understanding of ptype doping of ZnSe, and to the understanding of the lasing properties of ZnSe epitaxial layers and ZnSe-based heterostructures using external electron-beam or optical excitation. [3][4][5][6][7][8][9][10][11] Room-temperature optically pumped lasing of ZnSe-based QW heterostructures grown by MOVPE has been achieved by several groups, 3,4,6,7 using ZnSe/ZnSSe multiple-quantum-well ͑MQW͒ heterostructures 3,4,6 or ZnSe/ ZnMgSSe double heterostructures. 7 The main aim of our work was the investigation of the influence of the type of heterostructure, well width L z , and optical confinement factor ⌫ on the laser threshold and on the possibility of achieving high-temperature lasing.…”

“…For comparison, the shift of the electron-hole plasma ͑EHP͒ band in homogeneous ZnSe epilayers with a ZnMgSSe barrier layer between ZnSe and GaAs in the same range of I exc is about 13 meV, and in ZnSe:N layers the shift is approximately 20 meV. 11 We believe that the new emission band at high excitation intensity originates from recombination in an electron-hole plasma produced by a high nonequilibrium carrier concentration, which is most probably responsible for the gain mechanism in our structures.…”