Quaternary Alloy Infrared Heterojunction Detectors

Single heterojunction photodiodes suitable for the 1.0 to 1.3 µm spectral region of interest for fiber optics communication have been prepared from lattice-matched p-type epilayers of the quaternary III--V alloy semiconductor InGaAsP on n-type InP substrates. The characteristics of these heterojunctions are demonstrated by mesa photodiodes made from Zn-doped epilayers of composition In0.84Ga0.16As0.34P0.66 on Sn-doped InP. Their room temperature spectral response extends from the q, 0.96 µm self-filtering cutoff of the InP substrate to Ëœ 1.13 µm determined by the bandgap of this particular quaternary composition. Responsivities of 0.46 A/W and external quantum efficiencies of 0.54 are measured at 1.05 µm.