Homoepitaxial growth of (100) Si-doped β-Ga_(2)O_(3) films via MOCVD

Homoepitaxial growth of Si-doped β-Ga_(2)O_(3) films on semi-insulating(100) β-Ga_(2)O_(3) substrates by metalorganic chemical vapor deposition(MOCVD) is studied in this work. By appropriately optimizing the growth conditions, an increasing diffusion length of Ga adatoms is realized, suppressing 3D island growth patterns prevalent in(100) β-Ga_(2)O_(3) films and optimizing the surface morphology with [010] oriented stripe features. The slightly Si-doped β-Ga_(2)O_(3) film shows smooth and flat surface morphology with a root-mean-square roughness of 1.3 nm. Rocking curves of the(400) diffraction peak also demonstrate the high crystal quality of the Si-doped films. According to the capacitance–voltage characteristics, the effective net doping concentrations of the films are 5.41 × 10~(15) – 1.74 × 10~(20) cm~(-3). Hall measurements demonstrate a high electron mobility value of 51cm~2/(V·s), corresponding to a carrier concentration of 7.19 × 10~(18) cm~(-3) and a high activation efficiency of up to 61.5%. Transmission line model(TLM) measurement shows excellent Ohmic contacts and a low specific contact resistance of 1.29 × 10~(-4) Ω·cm~2 for the Si-doped film, which is comparable to the Si-implanted film with a concentration of 5.0 × 10~(19) cm~(-3), confirming the effective Si doing in the MOCVD epitaxy.

Homoepitaxial Growth and Characterization of 4H-SiC Epilayers by Low-Pressure Hot-Wall Chemical Vapor Deposition

Horizontal air-cooled low-pressure hot-wall CVD (LP-HWCVD) system is developed to get highly qualitical 4H-SiC epilayers.Homoepitaxial growth of 4H-SiC on off-oriented Si-face (0001) 4H-SiC substrates is performed at 1500℃ with a pressure of 1.3×103Pa by using the step-controlled epitaxy.The growth rate is controlled to be about 1.0μm/h.The surface morphologies and structural and optical properties of 4H-SiC epilayers are characterized with Nomarski optical microscope,atomic force microscopy (AFM),X-ray diffraction,Raman scattering,and low temperature photoluminescence (LTPL).N-type 4H-SiC epilayers are obtained by in-situ doping of NH 3 with the flow rate ranging from 0.1 to 3sccm.SiC p-n junctions are obtained on these epitaxial layers and their electrical and optical characteristics are presented.The obtained p-n junction diodes can be operated at the temperature up to 400℃,which provides a potential for high-temperature applications.

Chloride-based fast homoepitaxial growth of 4H-SiC films in a vertical hot-wall CVD

Chloride-based fast homoepitaxial growth of 4H-SiC epilayers was performed on 4° off-axis 4H-SiC substrates in a home-made vertical hot-wall chemical vapor deposition（CVD） system using H2-SiH4-C2H4-HCl.The effect of the SiH_4/H_2 ratio and reactor pressure on the growth rate of 4H-SiC epilayers has been studied successively.The growth rate increase in proportion to the SiH_4/H_2 ratio and the influence mechanism of chlorine has been investigated.With the reactor pressure increasing from 40 to 100 Torr,the growth rate increased to 52μm/h and then decreased to 47 μm/h,which is due to the joint effect of H_2 and HC1 etching as well as the formation of Si clusters at higher reactor pressure.The surface root mean square（RMS） roughness keeps around 1 nm with the growth rate increasing to 49 μm/h.The scanning electron microscope（SEM）,Raman spectroscopy and X-ray diffraction（XRD） demonstrate that 96.7 μm thick 4H-SiC layers of good uniformity in thickness and doping with high crystal quality can be achieved.These results prove that chloride-based fast epitaxy is an advanced growth technique for 4H-SiC homoepitaxy.

High-quality homoepitaxial layers grown on 4H-SiC at a high growth rate by vertical LPCVD

High quality,homoepitaxial layers of 4H-SiC were grown on off-oriented 4H-SiC（0001） Si planes in a vertical low-pressure hot-wall CVD system（LPCVD） by using trichlorosilane（TCS） as a silicon precursor source together with ethylene（C;H;） as a carbon precursor source.The growth rate of 25-30μm/h has been achieved at lower temperatures between 1500 and 1530℃.The surface roughness and crystalline quality of 50μm thick epitaxial layers（grown for 2 h） did not deteriorate compared with the corresponding results of thinner layers（grown for 30 min）.The background doping concentration was reduced to 2.13×10;cm;.The effect of the C/Si ratio in the gas phase on growth rate and quality of the epi-layers was investigated.