Graded Base Heterostructure Hot Electron Transistor
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
A hot electron-type transistor structure is constructed with a semiconductor (e.g., nGaAs) for the emitter and collector, and with an epitaxial n++ semiconductor with a smaller band gap (e.g., InGaAs) for the base layer. This will minimize base losses associated with scattering at the metal/semiconductor (base/collector) interface. Further, the emitter/base barrier is made larger than the base/collector barrier to improve the current gain. This is accomplished by grading the In concentration in the ternary semiconductor base layer. The figure illustrates the energy bands for the case of a GaAs/InGaAs/GaAs device, in which a larger In fraction at the emitter/base interface than at the collector/base interface results in a higher emitter/base barrier.