Shigeo Kaneda

MBE growth of 3C·SiC/6·SiC and the electric properties of its p-n junction

Crystal growth of 3C·SiC on a 6H·SiC substrate is performed to develop the practical device utilizing a p-n junction of SiC. The growth condition to obtain stoichiometric crystals relating to a substrate temperature Tsub, both molecular beam intensities JSi and JC and their ratio JSi/JC are established. To form a p-type 3C·SiC, we used a Si source containing B (boron) of proper atomic percentage in accordance with the dopant density. The p-n diode of p-3C·SiC/n-6H·SiC showed successfully rectified I–V characteristics and steep breakdown characteristics like the Si p-n junction.

Low‐temperature growth of 3C‐SiC by the gas source molecular beam epitaxial method

Single crystalline 3C‐SiC films were grown on a Si substrate by molecular beam epitaxy (MBE) using SiHCl3 and C2H4 gases. The optimal growth conditions were achieved at a growth temperature (Tsub ) of 1000 °C and a gas pressure ratio (PSiHCl3 /PC2H4 ) of 1/3 at PSiHCl3 =1×10−5 Torr. Prior to the essential growth of SiC, a carbonization process was performed with C2H4 gas only. A continuous observation by reflection high‐energy electron diffraction (RHEED) was performed throughout the process of crystal growth. A series of RHEED patterns revealed that carbonization film could be grown at 750 °C and the lattice mismatch between Si and SiC crystals was satisfactorily relaxed. All processes of crystal growth were performed at a relatively low temperature.

Carbonization process for low‐temperature growth of 3C‐SiC by the gas‐source molecular‐beam epitaxial method

Using the carbonization process, single‐crystalline SiC films were grown at substrate temperature (Tsub) in the range of 750–1050 °C by the gas‐source molecular‐beam epitaxial method. This process was performed by using C2H4 gas and a special growth method in which the temperature was raised at a predetermined rate (RT) during growth. To realize the growth of single‐crystalline carbonized films, it was found that a C2H4 gas pressure PC2H4=8×10−5 Torr and rising rate RT=25–25/3 °C/min were necessary. After the carbonization process, essential growth of SiC films using SiHCl3 and C2H4 gases in the range of gas pressure ratios PSiHCl3/PC2H4= (1)/(3) –5 (PSiHCl3=1–5×10−5 Torr) at Tsub=1000 °C was performed. In these all experimental ranges, single‐crystalline 3C‐SiC films could be grown.

Amorphous SiN films grown by hot‐filament chemical vapor deposition using monomethylamine

Hot‐filament chemical vapor deposition (hot‐filament CVD) of silicon nitride films has been studied using silane and monomethylamine as source gases for the deposition temperature 600–800 °C. The deposition rate was about one order larger than that of thermochemical vapor deposition (thermo‐CVD) using the same gases. The activation energy of the growth rate was 0.2 eV smaller than that of thermo‐CVD. The hydrogen content was below the detection limit of infrared absorption measurements even in the film deposited at 600 °C. The film surface deposited at 700 °C had a smooth specular surface and the flatness of the hot‐filament CVD films was the same as that of thermo‐CVD films deposited at 100–200 °C higher temperatures.

Low-temperature growth and its growth mechanisms of 3C-SiC crystal by gas source molecular beam epitaxial method

Abstract Low-temperature growth of epitaxial 3C-SiC films on the just cut and 4° off-Si(111) substrates were performed by gas source molecular beam epitaxial method. Also the irradiation effect of ArF laser was briefly examined. Two kinds of gaseous combinations such as SiHCl 3 -C 2 H 4 and SiHCl 3 -C 3 H 8 systems were used to achieve the stoichiometric growth at low temperature. These gases were first thermally cracked at 1000°C and deposited on the substrates. From detailed examinations of the reaction mechanism for this growt method, we concluded that the growth was performed under the conditions of a three-temperature method of MBE in both gaseous systems. Using these cracked species, 3C-SiC films having good crystallinity could be grown at 1000 and 800°C in the SiHCl 3 -C 2 H 4 and SiHCl 3 -C 3 H 8 systems, respectively. Currently, it seems that the growth temperature of 800°C is the lowest as compared with other works. We consider that such a low-temperature growth can be performed by the reactions of cracked species at the hollow bridge sites which exist on (111) terraced surface. The ArF laser irradiation was found to enhance the SiC crystallization reaction.

Single crystal growth of ZnS by the method of gas source MBE

Crystal growth of ZnS by a new type of MBE apparatus having a H2S gas source has been performed. The basic characteristics of the H2S gas source have been examined and an attempt to determine the optimum growth conditions has been made. In our present experiments, single crystalline films having fairly high quality have been obtained under suitable conditions, i.e., Tsub (substrate temperature) = 360°C, PH2S (inlet gas pressure of H2S) = 3×10−5 Torr, Tcr(H2S)(cracking temperature of H2S) = 920°C and JZn (Zn beam intensity) = (6−9)X1015 mol/cm2·s.

Growth of low stress SiN films containing carbon by magnetron plasma enhanced chemical vapor deposition

Abstract Low stress silicon nitride (SiN) thin films containing carbon were grown by magnetron plasma enhanced chemical vapor deposition (magnetron PECVD) using silane, monomethylamine and hydrogen as source gases. Various properties of the films such as internal stress, hydrogen content, composition, optical absorption and electrical resistivity were measured. The maximum optical gap obtained from optical absorption was 4.8 eV, and the maximum electrical resistivity was 5.5 × 1015ω cm. This electrical resistivity value is almost equal to that of the high-quality SiN films deposited by magnetron PECVD using silane and ammonia as source gases. Also, the internal stress of all films was compressive and the smallest value of the compressive stress was 1.1 × 108 N/m2, which is much smaller than that of the film from SiH4 and NH3.

Optimum growth condition of single‐crystalline undoped ZnS grown by the molecular‐beam‐epitaxial method using a H2S gas source

Crystal characterization by photoluminescence and x‐ray diffraction has been performed to find out the optimum growth condition of ZnS grown by the gas‐source molecular‐beam‐epitaxial (MBE) method. In this crystal growth, important parameters are the cracking temperature of H2S gas (Tcr), the film thickness (d), both molecular‐beam flux intensities (JZn and JΣS or inlet H2S gas pressure Pin), and substrate temperature (Tsub). A single crystal having a fairly high quality, whose half width of x‐ray diffraction FWHM is about 0.119° (the reference value of the GaAs substrate used is 0.093°), is obtained under the growth conditions Pin=1.4×10−5 Torr (corresponding flux intensity JΣS=7×1015 cm−2 s−1), JZn/JΣS=1, and Tsub=325 °C in the case of Tcr=780 °C and d≂1 μm.

Low hydrogen content silicon nitride films grown by chemical vapor deposition using microwave excited hydrogen radicals

A chemical vapor deposition method using hydrogen radicals excited by microwave plasma has been applied to obtain silicon nitride films of low hydrogen content. In this method, silane and monomethylamine were used as source gases. For a appropriate experimental condition, residual carbon and oxygen contents could be reduced to a small value and residual hydrogen content was smaller than ∼1 × 1022 cm-3. Also, the structure of hydrogen bonding and the structural change with time of the films were measured.

The influence of carbon addition on the internal stress and chemical inertness of amorphous silicon―nitride films

Abstract The internal stress, optical gap and chemical inertness of amorphous silicon-nitride films incorporating carbon prepared by rf magnetron sputtering were examined. The carbon composition of the films was less than 15 at%. The optical band gap was barely affected by the carbon addition. The internal stress was compressive in all films and increased up to 7.3 × 10 8 N/cm 2 in a-SiN: H films in proportion to the nitrogen content, and decreased to less than one-half in carbon-free films. The buffered HF etch rate increased to greater than 1 μm/min in proportion to the nitrogen content in SiN : H films. The etch rate decreased by about one order of magnitude with the addition of carbon.