Dual mode tilted-charge devices and methods

A method for providing and operating a device in a first mode as a light-emitting transistor and in a second mode as a high speed electrical transistor, comprising the steps of:

• providing a p-type GaAs semiconductor base region between n-type semiconductor emitter and collector regions;
• providing a quantum well in said base region;
• providing, in said base region between said quantum well and said collector region, a carrier transition region, said carrier transition region being GaAs doped less heavily p-type than the portion of said base region between said quantum well and said quantum well and said emitter region;
• applying a controllable bias voltage across the junction of said base and collector regions to control depletion of carriers in at least said carrier transition region;
• and
• applying signals with respect to said emitter, base, and collector regions to operate said device as either a light-emitting transistor or a high speed electrical transistor, depending on said controllable bias voltage;
• said step of applying said controllable bias voltage comprising applying said bias voltage to fully deplete carriers in said collector region, said carrier transition region, and a portion of said base region, for operation of said device as a high speed electrical transistor, the removal of said bias voltage resulting in operation of said device as a light-emitting transistor producing light emission from said base region.

A method for providing and operating a device in a first mode as a light-emitting transistor and in a second mode as a high speed electrical transistor, comprising the steps of:

• providing a p-type GaAs semiconductor base region between n-type semiconductor emitter and collector regions;
• providing a quantum well in said base region;
• providing, in said base region between said quantum well and said collector region, a p-type carrier transition region of semiconductor material having a wider bandgap than GaAs;
• applying a controllable bias voltage across the junction of said base and collector regions to control depletion of carriers in at least said carrier transition region;
• and
• applying signals with respect to said emitter, base, and collector regions to operate said device as either a light-emitting transistor or a high speed electrical transistor, depending on said controllable bias voltage;
• said step of applying said controllable bias voltage comprising applying said bias voltage to fully deplete carriers in said collector region, said carrier transition region, and a portion of said base region, for operation of said device as a high speed electrical transistor, the removal of said bias voltage resulting in operation of said device as a light-emitting transistor producing light emission from said base region.