Dielectrics for passivation of planar InP/InGaAs diodes |
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Authors: | G Unterbrsch HG Bach F Schmitt R Schmidt W Schlaak |
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Affiliation: | Heinrich-Hertz-Institut für Nachrichtentechnik Berlin GmbH, Einsteinufer 37, D-1000, Berlin 10, Germany |
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Abstract: | We have investigated dielectrics for passivating planar InP or InGaAs photodiodes: thermally evaporated Al2O3 and SiO, sputtered Si3N4 and SiO2 and also SiO2 using chemical vapour deposition. The measured bulk and field-effect properties of all dielectrics excluding sputtered SiO2 were suitable for this application. In planar InGaAs diodes with Cd diffused or Mg implanted p+-region a disordered dielectric/semiconductor surface led to high reverse current densities above 1 mA/cm2. In InP diodes with p+-diffusion and dielectrics exhibiting positive flatband voltages, e.g. Si3N4 and Al2O3, reverse current densities of 10 μA/cm2 were measured probably caused by a slight inversion of the semiconductor surface. With a SiO or CVD-SiO2 passivating layer on n-InP lowest leakage current densities (10 nA/cm2) were achieved. Very low dark-current planar photodiodes InP/InGaAsP/InGaAs have been fabricated using SiO passivation (30 nA/cm2). |
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