Papers by Author: Alla S. Tregubova

Abstract: Abstract Results of an epitaxial growth of 3C-SiC epilayers on Si (0001) and C(000¯1) faces of hexagonal 6H-SiC substrates are described. TEM study of grown layers as well as interface between cubic and hexagonal polytypes is presented. Difference between the layers on the Si and C faces are discussed.

Abstract: It is demonstrated that polytype-homogeneous, thick (>100 m) epitaxial 3C-SiC layers of good quality with diameters of no less than 25 mm can be grown on 6H-SiC substrates by sublimation epitaxy in vacuum. These layers can be used as seeds for growing bulk 3C-SiC crystals by modified Lely method.

Abstract: Photoluminescence (PL) spectra of 3C-SiC(n,p)/6H-SiC(n) and 3C-SiC(p)/15R-SiC(n) heterostructures have been studied. A broad structureless band, absent in PL spectra of n–n heterostructures, was observed in the spectrum of p–n heterostructures in the energy range 2.2–2.4 eV. It is suggested that this band is due to the presence of a 2D electron gas in a quantum well near the heterointerface. High (~ 4000 cm2/s V) value of electron mobility and the absence of any significant fall in the mobility temperature dependence at liquid-nitrogen temperatures confirm the existence of a 2DEG in the QW at the heterointerface.

Abstract: Highly doped p-3C-SiC layers of good crystal perfection have been grown by sublimation epitaxy in vacuum. Analysis of the photoluminescence (PL) spectra and temperature dependence of the carrier concentration shows that at least two types of acceptor centers at ~EV + 0.25 eV and at EV + 0.06-0.07 eV exist in the samples studied. A conclusion is made that layers of this kind can be used as p-emitters in 3C-SiC devices.

Abstract: 3C-SiC epitaxial layers with a thickness of up to 100 μm and area of ~0.3-0.5 cm2 have been grown by sublimation epitaxy on hexagonal (6H-SiC) substrates at a maximum growth rate of about 200 μm per hour. The epilayers obtained are of n-type (Nd-Na ~ 1017 -1018 cm-3). According to X-ray data, the epitaxial layers are composed of the 3C-SiC polytype, without inclusions of other polytypes. The donor-acceptor (Al-N) recombination band with hνmax ~ 2.12 eV predominates in the photoluminescence (PL) spectrum. A detailed analysis of a PL spectrum measured at 6 K is presented. A conclusion is made that the epitaxial layers can be used as substrates for electronic devices based on 3C-SiC.

Abstract: Investigation of the multilayer 6H(n+)/3C(n)/6H(p+)-SiC heterostructure grown by sublimation epitaxy show that the injection electroluminescence (IEL) in the green region (hνmax≈2.30-2.35eV) of spectrum is dominant. This band is close to the electroluminescence peak due to defects in 6H-SiC but also can be due to free exciton annihilation in a quantum well in 3C-SiC at the 6H/3C-SiC heterointerface. At high current the IEL peak at hνmax≈2.9 eV is found. This peak (and also two another peaks in blue part of spectra: hνmax≈2.6 eV and hνmax≈2.72 eV) can be attributed to recombination in 6H-SiC. The forward current-voltage characteristics for best structures are close to those for ideal 6H-SiC pn homostructure and characterized by abrupt breakdown. A lot of structures are characterized by barrier type excess current. Structure in the region of evident 3C-SiC inclusion is characterized by high forward and reverse excess currents.