Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 9: SiC

HL 9.2: Talk

Monday, March 22, 2010, 11:45–12:00, H13

Analysis of the Temperature-Dependence of the Leakage Current of 3C-SiC p⁺-n Diodes Caused by Extended Defects — •Bernd Zippelius¹, Michael Krieger¹, Heiko B. Weber¹, Gerhard Pensl¹, Takamitsu Kawahara², and Hiroyuki Nagasawa² — ¹Lehrstuhl für Angewandte Physik, Universität Erlangen-Nürnberg, Staudtstr. 7/A3, D-91058 Erlangen, Germany — ²SiC Development Center, Hoya Corporation, 1-17-16 Tanashioda, Sagamihara, Kanagawa 229-1125, Japan

A large leakage current (I_R) is observed at reverse bias (V_R) in 3C-SiC p⁺-n diodes. This leakage current is caused by a high density of stacking faults (SFs). We used an n-type 3C-SiC epilayer (thickness = 13 µm, [N] = 7 × 10¹⁵ cm⁻³) and implanted Al ions to form the p-emitter (φ = 100 µm), which is surrounded by 6 guard rings (depth = 1 µm, [Al] = 1 × 10¹⁸ cm⁻³). Al contacts are deposited on the emitter. The temperature dependence of I_R is studied in the temperature range from 100 K to 295 K. The extended defects under the contacts were investigated by Electron Beam Induced Current (EBIC) and Photo Emission Microscopy (PEM). It turns out that I_R is thermally activated for reverse voltages V_R < |170| V. We propose that within this voltage range I_R originates from thermally assisted tunneling of electrons and holes from band-like states of the SFs into the conduction and valence band, respectively. For V_R > |170| V, the thermal barrier is strongly reduced and direct tunneling dominates. These dependences are simulated in the framework of a simplified model which qualitatively describes the temperature behaviour of the experimental data.