In_xGa_(1-x)As/InP quantum well structures grown on [111]B InP

摘要

We report growth and characterization details of lattice matched and coherently strained In_xGa_(1-x)As/InP quantum well structures grown on misoriented [111]B InP substrates. Photoluminescence from a range of such structures, grown on substrates with optimum misorientation, show linewidths as good or better than equivalent [100] layers. Multiquantum well (MQW) samples with relatively modest compressive strain show X-ray diffraction data characteristic of highly uniform pseudomorphic quantum wells. With increased strain (x = 0.63), relaxation is evident through a degradation of the diffracted peak widths and through the observation of defects in the surface mqrphbl-ogy. Fabricated strained' p-i(MQW)-n diode structures exhibit low reverse leakage current densities (e.g.j = 6 μA/ cm~2). Room temperature photocurrent measurements on these devices show a strong excitonic blue shift (1,5 nm) with applied bias, as a consequence of the built-in piezoelectric field. The rate of peak shift, up ,to 8 nm/V, demonstrates excellent potential for low voltage optical modulator applications at around 1.55 μm wavelength.