Heterojunction detectors from UV to IR

Heterojunction detectors used as free-carrier and intervalence band detectors for a wide wavelength region are presented. Using a well-studied III-V system of GaAs/Al_xGa_1-xAs to cover a wide wavelength range from UV to far-infrared (THz) is an important development in detector technology. Using the intervalence band (heavy hole, light hole and split off) transitions for high operating temperature detection of mid Infrared radiation is discussed. A promising new way to extend the detection wavelength threshold beyond the standard threshold connected with the energy gap in a GaAs/Al_xGa_1-xAs system is also presented.