| 摘要 |
1,028,417. Semi-conductor devices. SOC. EUROPEENE DES SEMI CONDUCTEURS. June 7, 1963 [June 8, 1962], No. 22782/63. Heading H1K. A photo-voltaic cell is made from a monocrystalline wafer of semi-conductor material which contains at least one rectifying junction and which has its two major faces effectively inclined with respect to one another, this being achieved either by wholly inclining the faces or by inclining elements of one or both major faces. The angle of inclination is made such that radiation incident normally on the entry surface undergoes a series of total internal reflections at the insides of the two major faces. The angle of inclination may be halved provided that one major face is given a metallic coating so that the first reflection occurs at a metallic surface. Because of the long radiation path length produced in the body, radiation having an energy only slightly above the band gap energy of the semi-conductor may be readily absorbed. Each of the specific embodiments has one plane major face. In one (PN) the second face is inclined in its entirety; in a second (PN) a series of parallel grooves of saw-tooth section are formed on the second face; in a third (PIN) the second surface takes the form of a hollow cone; in a fourth (PN) the second face is formed by two mutually inclined planes which make equal angles with the first major face; and in the fifth (PN) the second face is etched to cover it with pyramids formed by selective attack on the various crystal planes. The semi-conductor material may be silicon. The etchant used in forming the fifth embodiment is a specified mixture of hydrofluoric acid, nitric acid, acetic acid, and bromine. |
