Growth and characterization of a bound-to-quasi-continuum QWIP with Al-graded triangular confinement barriers

A bound-to-quasi-continuum GaAs-AlGaAs quantum-well infrared photodetector (QWIP) with absorption peak centered at 9 mu m has been grown and character ized. Instead of the abrupt interfaces between AlGaAs layers, a different c onfiguration based on AlGaAs graded triangular barriers is used in this wor k. This structure allows one to grow all the layers with one single Al cell avoiding growth interruption. The detectors show symmetric behavior in the current versus voltage characteristic. Peak responsivities as high as 0.5 A/W using a tilted substrate holder and without any light coupling mechanis m were measured. Besides, photocurrent response in normal incidence, withou t diffraction grating, was also observed.