Abstract: In an HEMT, a channel forming layer is arranged above a semi-insulating substrate via a buffer layer. A spacer layer is arranged on the channel forming layer and an electron supplying layer and a Schottky contact layer are sequentially arranged on the spacer layer. A diffusion preventing layer, for preventing a metal element of a gate electrode from diffusing into the channel forming layer, is arranged in the Schottky contact layer.

Abstract: Disclosed is an ultra high frequency radio communication apparatus having: a receiver antenna; a transmitter antenna; an IC chip being electrically connected to the receiver antenna and the transmitter antenna; a substrate on which the receiver antenna, the transmitter antenna and the IC chip are mounted; an input terminal for inputting to the IC chip a base band input signal; an output terminal for outputting a base band output signal from the IC chip; and a control signal terminal for inputting a control signal for controlling the IC chip to the IC chip. The IC chip is placed in a shielding space such that the cut-off frequency of the shielding space is higher than the frequency of a carrier signal for radio communication.

Abstract: A high electron mobility transistor (HEMT) comprises an InGaAs channel layer formed on a semi-insulating InP substrate via a buffer layer, and an n-type InA.iota.As electron supply layer formed on the channel layer via a spacer layer. On the electron supply layer, formed is an InGaA.iota.P Schottky contact layer, on which a Schottky gate electrode is formed. Source and drain electrodes are formed on the Schottky contact layer via an InGaAs ohmic contact layer, interposing the Schottky gate electrode therebetween. Thus, there is provided an InA.iota.As/InGaAs HEMT having a high gate breakdown voltage, and exhibiting a small variance of characteristics.

Abstract: A p-type GaAs or AlGaAs thin film is formed by a MOCVD method. In the growing step of the thin film, the thin film is doped with a high concentration of carbon atoms forming an acceptor level such that the carrier concentration of the thin film falls within the range of between 1.times.10.sup.18 cm.sup.-3 and 1.times.10.sup.20 cm.sup.-3. At least one of trimethyl gallium and trimethyl aluminum is used as a raw material gaseous compound of III-group element, and arsine is used as a raw material gaseous compound of V-group element. The thin film is formed by an epitaxial growth under the molar ratio V/III of the V-group element supply rate to the III-group element supply rate, which is set at such a small value as 0.3 to 2.5, the temperature of 450 to 700.degree. and the pressure of 1 to 400 Torr. The thin film formed under these conditions exhibits a mirror-like smooth surface, and the film-growth rate is dependent on the supply rate of the V-group element.

Abstract: An apparatus for growing a compound semiconductor on a substrate by molecular beam epitaxy, includes a growth chamber, and Knudsen cells, disposed in the growth chamber, for generating molecular beams of source materials for the compound semiconductor independently. An ion gauge is disposed in the growth chamber, for measuring intensities of the molecular beams. A heater disposed in the growth chamber heats the substrate to a growth temperature of the compound semiconductor. A heating element heats the heater and the ion gauge to evaporate contamination materials including the source materials deposited on said substrate heating means and said measuring means after the growth of the compound semiconductor. An evacuater is provided to evacuate the growth chamber to a vacuum.