| 摘要 |
1,196,682. Semi-conductor devices. MATSUSHITA ELECTRIC INDUSTRIAL CO. Ltd. 5 July, 1967 [8 July, 1966; 21 July, 1966 (3); 29 July, 1966], No. 31051/67. Heading H1K. A solid state oscillator element comprises a thin film 32 of polycrystalline semi-conductor material situated on a conducting substrate 31 and having an upper electrode 35. The semiconductor material is of the type having two energy minima in the conduction band at different wave-vector values, electrons in the higher energy minimum having a lower mobility than in the lower one so that Gunn-effect oscillations can occur. Suitable materials are GaAs or GaSb, and Si, Ge and InSb are also referred to. The film 32 may be uniformly polycrystalline, or may include preferentially oriented polycrystalline regions 33, and the inclusion of deep level impurities such as O 2 or Au is stated to decrease the threshold field for production of oscillations. A method of making such an element comprises depositing a thin film 32 of GaAs on a Ta substrate 31 by vacuum evaporation from separate sources of Ga and As, the Ga: As atomic ratio varying in the range 0À2 to 3À0. Mo or SnO 2 are alternative substrate materials, and gas or liquid phase reactions may also be used to produce the GaAs body. O 2 may be incorporated into the film 32 from a heated gallium oxide source, gallium chloride also being heated in the same silica tube. The upper electrode 35 is formed by evaporation of Au, A1 or Sn. For operation the element is mounted in a resonant cavity. |
