Abstract: An emitter contact layer, an emitter layer, a base layer, a p-type base layer, a collector layer, and a sub-collector layer are crystal-grown over a first substrate in this order with the main surface as the Group III polar surface. The emitter contact layer includes a nitride semiconductor that is made n-type at a relatively high concentration. The emitter layer includes a nitride semiconductor having a bandgap larger than that of the nitride semiconductor constituting the emitter contact layer. The base layer includes an undoped nitride semiconductor having a bandgap smaller than that of the nitride semiconductor constituting the emitter layer. The p-type base layer includes the same nitride semiconductor as the base layer and made p-type.

Abstract: A first collector layer is composed of n-type InP (n-InP) doped with Si at a low concentration. A second collector layer is composed of non-doped InGaAs. A base layer is composed of p-type GaAsSb (p+-GaAsSb) doped with C at a high concentration. An emitter layer is composed of a compound semiconductor different from that of the base layer, and has an area smaller than the base layer in a plan view. An emitter layer can be composed of, for example, n-type InP (n-InP) doped with Si at a low concentration.

Abstract: An integrated circuit includes a resistive material layer formed on a substrate, a metal layer formed on the resistive material layer, a bipolar transistor formed on the substrate, and a resistive element formed on the substrate. The bipolar transistor includes, as a sub-layer, the metal layer formed in a first region, and also includes a collector layer formed on the sub-collector layer. The resistive element is constituted by the resistive material layer formed in a second region.

Abstract: A first collector layer is composed of n-type InP (n-InP) doped with Si at a low concentration. A second collector layer is composed of non-doped InGaAs. A base layer is composed of p-type GaAsSb (p+-GaAsSb) doped with C at a high concentration. An emitter layer is composed of a compound semiconductor different from that of the base layer, and has an area smaller than the base layer in a plan view. An emitter layer can be composed of, for example, n-type InP (n-InP) doped with Si at a low concentration.

Abstract: An emitter contact layer, an emitter layer, a base layer, a p-type base layer, a collector layer, and a sub-collector layer are crystal-grown over a first substrate in this order with the main surface as the Group III polar surface. The emitter contact layer includes a nitride semiconductor that is made n-type at a relatively high concentration. The emitter layer includes a nitride semiconductor having a bandgap larger than that of the nitride semiconductor constituting the emitter contact layer. The base layer includes an undoped nitride semiconductor having a bandgap smaller than that of the nitride semiconductor constituting the emitter layer. The p-type base layer includes the same nitride semiconductor as the base layer and made p-type.

Abstract: An element portion is formed on a heat dissipation substrate, and the element portion includes a collector layer, a base layer, an emitter layer, an emitter cap layer, an emitter electrode, and a base electrode. A metallic emitter heat dissipation via that connects an emitter wiring to an emitter heat dissipation pad is provided, and a metallic base heat dissipation via that connects a base wiring to a base heat dissipation pad is also provided.

Abstract: An integrated circuit includes a resistive material layer formed on a substrate, a metal layer formed on the resistive material layer, a bipolar transistor formed on the substrate, and a resistive element formed on the substrate. The bipolar transistor includes, as a sub-layer, the metal layer formed in a first region, and also includes a collector layer formed on the sub-collector layer. The resistive element is constituted by the resistive material layer formed in a second region.

Abstract: An improved wheelchair which can pass through a narrow aisle, for example in an airplane. The wheelchair has an axle with a pair of main wheels, removably mounted to the wheelchair frame so as to be removable without lifting the frame, as well as auxiliary wheels narrow enough to pass through such an aisle. The main wheels are sufficiently spaced for stable travelling.

Abstract: A folding baby carriage foldable into the shape of a walking stick is known. The folding baby carriage of this invention is provided with a folding protective frame or handrail to protect the baby from dropping out of the carriage.