Abstract: A high-frequency module has a wiring board including a dielectric substrate, a line conductor that is formed on a first surface of the dielectric substrate, and a first grounding conductor layer that is formed on a second surface opposed to the first surface of the dielectric substrate, and that has a first opening and a second opening disposed around the first opening; and a waveguide that is connected to the second surface, has an opening opposed to the first opening, and is electromagnetically coupled to the line conductor. The wiring board has a vertical choke portion that at least partially extends from the second opening in a direction perpendicular to the second surface. Furthermore, a horizontal choke portion is formed between the wiring board and the waveguide, along the second surface between the opening of the waveguide and the second opening.

Abstract: In a method of processing a compound semiconductor wafer to deposit or form a specific layer on a wafer surface, to partially remove the specific layer to partially expose the wafer surface, and to etch a partially exposed area of the wafer, etching is performed by irradiating an electron beam and a specific gas which may be, for example, chlorine gas, bromine gas, iodine, or their compounds. Portions subjected to irradiation of both the electron beam and the specific gas are etched from the wafer. The specific layer is deposited or formed in the form of an oxide layer on the wafer surface by spraying an oxygen gas onto the wafer surface with light irradiated on the wafer surface. Such an oxide layer may be either an adsorbed molecular layer of the oxygen gas or a chemically reacted layer which results from reaction of the oxygen gas with the wafer by the help of irradiation of the light. Alternatively, the specific layer may be either a sulphide layer or a nitride layer.

Abstract: An avalanche photodiode having a semiconducting light absorbing layer and an overlying avalanche gain layer of wide band-gap. The usual heavily doped region is formed in the avalanche gain region to form an abrupt p-n junction. Two semiconducting guard rings are formed around the heavily doped region. The doping of both rings provide graded p-n junctions with the avalanche gain layer. The inner guard ring extends more deeply into the avalanche gain layer than either the outer ring or the heavily doped region.