Wide bandgap over 3 eV and high p-doping BeZnTe grown on InP substrates by molecular beam epitaxy

BeZnTe II-VI compound ternary alloys with various Be composition (x(Be)) were grown on InP substrates by molecular beam epitaxy. From absorption coefficient measurements at room temperature. the bandgap energies (E-g) were evaluated as a function of x(Be). The bandgap energy monotonically increases from 2.24 to 3.29 eV when increasing x(Be) from 0 to 0.62 By fitting a quadratic equation in terms of x(Be) to the E-g values, E-g = 2.24(1 - x(Be)) + 4.1x(Be) + 0.1x(Be)(x(Be) - 1) is obtained, and tho bowing parameter is seen to be as small as 0.1eV. Thus, the E-g value of BeZnTe, when the lattice constant is matched to InP, is estimated to be 3.1eV. p-type doped BeZnTe alloys were grown using an RF-radical nitrogen source. A high hole concentration of 4.8 x 10(18) cm(-3) was obtained for a Be0.4Zn0.6Te sample with a wide bandgap of 2.97eV. These results suggest that BeZnTe is very promising for p-cladding layer materials in short wavelength II-VI laser diodes. (C) 2000 Elsevier Science B.V. All rights reserved.