Defect- and phonon-assisted tunneling in LPE In1−xGaxP1−zAsz DH laser diodes (λ∼1 μm)

Abstract

Tunnel diode I‐V, dI/dV, and d²I/dV² characteristics are used to examine defect effects and phonon energies in In_1−xGa_xP_1−zAs_z double‐heterojunction lasers (λ‐1.1 μm) grown by liquid‐phase epitaxy on InP substrates. Similar to the usual conductance minimum observed at zero bias, a conductance minimum in the dI/dV characteristics is observed at small forward bias (40⩽V⩽60 meV) and is identified as two‐step tunneling (via defects) to Zn‐acceptor states on the p‐type side of the junction. An increase in the conductance is observed below the region of carrier injection and is attributed to tunneling from residual acceptor states on the n‐type side of the junction. Fine structure in the dI/dV and d²I/dV² characteristics permits the identification of optical phonon energies at two In_1−xGa_xP_1−zAs_z compositions (x=0.12, z=0.26; x=0.16, z=0.35) and in this region indicates two‐mode behavior for the quaternary alloy.