Transistors

摘要

1,108,774. Semi-conductor devices. INTERNATIONAL BUSINESS MACHINES CORPORATION. 24 Aug., 1965 [13 Oct., 1964], No. 36220/65. Heading H1K. A method of making a transistor includes the steps of providing a body of semi-conductor material having successive layers alternating in conductivity type, the material having the property that the mobility in it of one type of carrier is substantially greater than the mobility of the other type of carrier, and defining the active portions of the emitter and base regions in the body by alloying an electrode through the emitter region, which is located at the surface of the body, to reach the base region immediately below the emitter region, the emitter region having an impurity concentration which is substantially less than the impurity concentration in the base region at the interface between the two regions. Suitable semi-conductor materials are gallium arsenide, in which the electron-hole mobility ratio is about 11, and indium antimonide in which the ratio is 30-50. In the preferred embodiment a lightly doped N-type layer 1 is formed epitaxially on a highly doped N-type substrate 2 and an acceptor impurity such as zinc is diffused into the layer 1 to produce a P + base region 3. The impurity concentration at the surface of the region 3 is about 1018 atoms/c.c. A lightly doped N-type emitter region 4 having an impurity concentration of about 1017 atoms/c.c. is then epitaxially deposited on the region 3 at such a temperature that the diffusion of impurities is not significant. The impurity in the region 4 may be selenium. A base electrode 6 is formed by alloying zinc through the region 4, rapid heating to the eutectic point followed by rapid cooling producing the regrowth region 5. The emitter electrode 7 is formed as an ohmic contact to the active central portion of the emitter region.