Papers by Author: Marina G. Mynbaeva

Abstract: Schottky-barrier diodes with a diameter of ~10 μm are fabricated on n-GaN epitaxial films grown by hydride vapor-phase epitaxy (HVPE) on sapphire substrates. The changes in the parameters of the diodes under irradiation with 15 MeV protons are studied. The carrier rate was found to be 130-145 cm^-1. The linear nature of the dependence N = F (D) (N is carrier concentration, and D, the irradiation dose) shows that compensation of the material is associated with transition of electrons from shallow donors to deep acceptor levels which are related to primary radiation defects.

Abstract: Nonequilibrium-charge transport has been studied in a structure with a Schottky barrier fabricated on a CVD-grown n-4H-SiC film. The charge introduced by single α-particles was recorded by nuclear spectrometric techniques. The maximum electric field strength in the structure was 1.1 MV/cm. The recorded charge as a function of the reverse bias applied to the structure shows a superlinear rise. Simultaneously, the width of the amplitude spectrum increased superlinearly, too. The observed effect is attributed to the initial stage of impact ionization. The manifestation of the process at unusually low fields (~1.0 MV/cm) is accounted for by specific features of the charge generation process. The carriers generated by a α-particle are found to be originally "heated". The results obtained allow prognostication of the appearance of SiC detectors of the "proportional counter" type in the near future. This is enabled by the advances made in the field of high-voltage electronics in obtaining in practice the required electric field strengths.

Abstract: An effective low-cost technique for rapid characterization of SiC ingots at the early stage of substrate manufacturing process is proposed. The method allows for revealing simultaneously open-micropipes, polytype inclusions, low grain boundary regions, and non-uniform resistivity. The idea of the method is to subject full-size single SiC wafer cut from an ingot to anodization treatment. The porous structure formed as a result of the treatment decorates existing defect regions via the effect of non-homogeneity in the porous structure caused by the defect-related internal stress, as well as by non-uniformity in the doping level across the wafer. The method is inexpensive, not time consuming and not fully destructive. It can also be combined with the standard selective KOH-etching technique.

Abstract: Thermal stability of porous SiC (PSC) with nano-, micro- and double-layer porous structure is assessed through annealing the material at T=900–1700 0C in vacuum and Ar. Changes in composition of PSC under thermal treatment are correlated with porous structure modification. Limitations in PSC technology and applications due to compositional and structure evolution at high temperatures are discussed.