Long-wavelength (0.1-1.6 mu m) In/sub 0.53/(Ga/sub x/Al/sub 1-x/)/sub 0.47/ As/In/sub 0.53/Ga/sub 0.47/As MSM photodiode

InGaAs metal-semiconductor-metal photodetectors for long wavelength optical communications

“…As discussed in the introduction, the growth of a thin layer of lattice-matched Iq,52A1,,4,As on the Iq,53G%,47As has proved to be the most successful technique for producing low leakage detectors [16]- [20], [22]. The III,,,,A~,,~~As (E, = 1.47 V) has a high Schottky barrier height of -0.8 V [23] and the thin epitaxial layer has the effect of raising the Schottky barrier on n--InGaAs, which is only -0.2 V, and limiting the dark current [ 161- [22].…”

“…Breakdown would therefore appear to arise from current flow across the barrier. Avalanche has often been cited as a potential source of breakdown [16], [22], [28]; the spacings between the fingers have sometimes been recessed [28] and rounded electrode structures have even been used [ 151. However, the breakdown biases observed experimentally are rather lower than those expected for avalanching, but are consistent with the dominance of a tunnel current through trapezoidal InAlAs barriers.…”

“…The III,,,,A~,,~~As (E, = 1.47 V) has a high Schottky barrier height of -0.8 V [23] and the thin epitaxial layer has the effect of raising the Schottky barrier on n--InGaAs, which is only -0.2 V, and limiting the dark current [ 161- [22].…”

“…Recently InP : Fe, which pins the Fermi level at midgap has also been employed [15], though this too produced devices with a significant pulse response tail and internal gain. The most promising barrier enhancement technique reported to date has been the growth of a thin layer of undoped latticematched InAlAs [16]- [22] on the InGaAs. InAlAs lattice matched to InP (E, = 1.47 V) has a high Schottky barrier of -0.8 V [23] and a thin layer grown epitaxially on InGaAs has the effect of raising both the electron and hole barriers.…”

“…InAlAs lattice matched to InP (E, = 1.47 V) has a high Schottky barrier of -0.8 V [23] and a thin layer grown epitaxially on InGaAs has the effect of raising both the electron and hole barriers. Both Organo-Metallic Chemical Vapor Deposition (OMCVD) grown 1161, [18]- [20] and MBE grown [17], [22] material has yielded devices with good performance characteristics. In the following sections, most of the experimental results reported will be for devices grown by low pressure (76 torr) OMCVD, which is the growth process used by the authors.…”