| 摘要 |
<PICT:0998211/C6-C7/1> Monocrystalline semi-conductor material, such as germanium, is produced from a gas phase by exposing a substrate to a stream of gas containing molecules which include reducible atoms of the semi-conductor material, at a temperature at which the molecules adhere to the substrate surface but do not decompose, and then reducing the atoms of the molecules adhering to the substrate surface followed by epitaxial growth, on the reduced atoms, of additional semi-conductor material from the gas until the desired thickness is obtained. In one embodiment, Fig. 1, germanium tetrachloride in a dry deoxidized hydrogen stream, in a concentration of about 0.1 mol per cent, is passed over a quartz substrate 23, heated to 500 DEG C., producing an adherent film of HGeCl3. The film is reduced to a germanium film in dry, deoxidized hydrogen at 650 DEG C. and the quartz surface is then exposed to a stream of GeCl4 in H2, as before, together with 0.001 mol per cent of boron tribromide at 500 DEG C. to deposit epitaxially P-type germanium on the germanium-coated quartz surface. The flow of BBr3 is interrupted and a stream of PCl3 is substituted, growing an additional epitaxial layer of N-type germanium. Other possible dopant sources are AsCl3 and AsBr3. A further embodiment, Fig. 3 (not shown), utilizes an intermediate oxidation step providing a mask for producing epitaxial growth on selected areas. In this case an anodized molybdenum or tungsten substrate is provided with a polar gas film by exposure to SiCl4 gas in H2 at between 730-910 DEG C., which is then reduced to silicon in a hydrogen stream at 950 DEG C., so producing a silicon film on the anodized surface. The silicon film is then oxidized to SiO2 by exposure to water vapour or oxygen and, after selective etching in hydrofluoric acid, epitaxial growth through the masking pattern is continued, providing a film of HSiCl3. BBr and subsequently PCl3 gases are introduced at this stage, providing the necessary doping to form p-n junctions. |
