MIS capacitor studies on silicon carbide single crystals

Cubic SIC metal-insulator-semiconductor (MIS) capacitors with thermally grown or chemical-vapor-deposited (CVD) insulators were characterized by capacitance-voltage (C-V), conductance-voltage (G-V), and current-voltage (I-V) measurements. The purpose of these measurements was to determine the four charge densities commonly present in an MIS capacitor (oxide fixed charge, N(f); interface trap level density, D(it); oxide trapped charge, N(ot); and mobile ionic charge, N(m)) and to determine the stability of the device properties with electric-field stress and temperature. The section headings in the report include the following: Capacitance-voltage and conductance-voltage measurements; Current-voltage measurements; Deep-level transient spectroscopy; and Conclusions (Electrical characteristics of SiC MIS capacitors)

Electrical Characterization of 4H-Silicon Carbide P-N Junction Diodes

The current conduction mechanisms of 4H-SiC p+n mesa diodes were studied using current-voltage-temperature (I-V-T), capacitance-voltage-temperature (C-V-T), deep level transient spectroscopy (DLTS), optical observations, and reverse breakdown measurements. Temperature and voltage dependencies of diffusion, recombination, and tunneling current processes are shown to be consistent with Sah-Noyce-Shockley theory. Recombination currents having an ideality factor of A=1.85-2.1 yielded an activation energy of EA=1.56 eV, whereas for ideal recombination, A=2 and EA=1.6 eV. Forward I-V curves of poor diodes dominated by tunneling and recombination processes, showing low reverse breakdown voltages of approx. 100 V, can be correlated to DLTS results which show large defect concentrations, and spectral observations indicating radiative recombination via defect sites. On the other hand, well-behaved diodes exhibited a breakdown voltage at approx. 450 V, a spectral output centered at 385 µm, and recombination-to-diffusion current ratios of 1012 - 1029 that agree with theory. C-V-T, DLTS, and reverse I-V-T data revealed several defect centers. C-V-T and reverse I-V-T measurements yielded an energy level at approx. 70 and approx. 62 meV, respectively, which is possibly attributable to nitrogen donor levels. Reverse I-V-T and DLTS results, in approximately half of the diodes tested, yielded a second trap level at 173 ±19 and 150 ±34 meV, respectively. Approximately 20% of the well-behaved diodes tested were found to breakdown unexpectedly at reverse biases as low as 95 V. It is believed that this unexpected breakdown is due to nanopipe defects in the diodes

Volume 72 - Issue 4 - January, 1961

https://scholar.rose-hulman.edu/technic/1055/thumbnail.jp

Silicon-on ceramic process: Silicon sheet growth and device development for the large-area silicon sheet task of the low-cost solar array project

The technical feasibility of producing solar-cell-quality sheet silicon to meet the Department of Energy (DOE) 1986 overall price goal of $0.70/watt was investigated. With the silicon-on-ceramic (SOC) approach, a low-cost ceramic substrate is coated with large-grain polycrystalline silicon by unidirectional solidification of molten silicon. This effort was divided into several areas of investigation in order to most efficiently meet the goals of the program. These areas include: (1) dip-coating; (2) continuous coating designated SCIM-coating, and acronym for Silicon Coating by an Inverted Meniscus (SCIM); (3) material characterization; (4) cell fabrication and evaluation; and (5) theoretical analysis. Both coating approaches were successful in producing thin layers of large grain, solar-cell-quality silicon. The dip-coating approach was initially investigated and considerable effort was given to this technique. The SCIM technique was adopted because of its scale-up potential and its capability to produce more conventiently large areas of SOC