| 摘要 |
<p>996,937. Lasers. INTERNATIONAL BUSINESS MACHINES CORPORATION. Feb. 5, 1964 [Feb. 21, 1963], No. 4814/64. Heading H3B. [Also in Division H1] An injection laser is produced by first cleaving a semi-conductor crystalline wafer along an edge plane of minimum bond strength to establish a reference plane, establishing a pattern on one surface of the wafer oriented relatively to the reference plane, diffusing an impurity in to the wafer surface in accordance with the pattern, and subsequently cleaving the wafer along a further plane which is parallel to the reference plane. The semiconductor wafer is cut from a parent crystal of gallium arsenide and is cleaved along the crystalline plane (110), Figure 4a, by a tool 46 to form the reference plane. As shown in Figure 4b, fine wires 49 are then positioned on the wafer orthogonal to the reference plane which mask strips of the wafer surface when a layer of silicon monoxide 48, Fig. 4c, is deposited by vacuum evaporation. After the wires are removed, the uncoated strips on the n-type semi-conductor surface provide regions where a p-type impurity vapour, such as zinc, is able to diffuse into the semi-conductor material to form the radiating junctions. The p-type region may be coated with an evaporated layer of indium to which an electrode may be attached. The bottom of the structure is then lapped so as to provide a required thickness, e.g. 5 mils. The group of semi-conductor devices are then separated into units by cutting between the p-type regions in the direction of arrow 50. Finally each unit is formed into the desired operational length by cleaving with a tool 54 along the 110 plane, Fig. 4b, the two parallel cleavage planes being inherently optically flat. An alternative method of forming the p-type regions is to cut a series of parallel grooves into the top surface of the wafer prior to vapour deposition of the p-type impurity. Subsequently the top surface is lapped down so that the diffused impurity remains only in the grooves. A coating may be placed over the top surface, or alternatively an epitaxial growth of gallium arsenide or other compatible material can be made on the upper surface prior to the lapping operation. A further method is to coat the crystal with silicon monoxide, and then with an etch resist which is selectively illuminated by the required pattern subsequent to etching. The diffusion operation then takes place. An alternative form of injection laser, Fig. 5 (not shown), has a cruciform p-type impurity zone formed by the process.</p> |
