Light detector using intersub-valence band transitions with strained barriers
AssigneeUniversity of Southern California
InventorsRoger T. Kuroda, Elsa M. Garmire
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Abstract
An intersub-valence band quantum well detector (52), comprising alternating quantum wells (30') and barriers (32'), provided with differential strain permits obtaining hole mean free paths similar to the electron. Consequently, the gain and responsivity should dramatically increase. In addition, the absorption coefficient should increase, while the noise current should decrease; thus, the quantum efficiency and the detectivity (D*) should increase, compared to a detector without the added differential strain.
Claims15
A detector for detecting light having a wavelength and comprising a plurality of alternating quantum wells and barriers formed either on a substrate or on a buffer layer formed on a supporting substrate, said quantum wells and barriers formed from semiconductor materials with p-doping within at least one of (a) said plurality of quantum wells and (b) said plurality of said barriers, having light holes generated by incident light from heavy holes due to intersubvalence band transitions, said detector operating by means of predominantely light holes which remain light holes in said barriers as a result of tensile strain sufficient to induce an energy difference between said light holes and said heavy holes of greater than 0.5 k.sub.B T, where k.sub.B is the Boltzmann constant and T is the operating temperature in kelvins, with said light holes having a lower energy than said heavy holes.
A two-color detector employing a heavy hole to light hole transition to detect light at a first wavelength, and the heavy hole to split-off transition to detect light at a second and different wavelength, said heavy hole to light hole transition achieved by a plurality of alternating quantum wells and barriers formed either on a substrate or on a buffer layer formed on a supporting substrate, said quantum wells and barriers formed from semiconductor materials with p-doping within at least one of (a) said plurality of quantum wells and (b) said plurality of said barriers, with said light holes generated by incident light from said heavy holes due to intersubvalence band transitions, said light holes remaining light holes in said barriers as a result of tensile strain sufficient to induce an energy difference between said light holes and said heavy holes of greater than 0.5 k.sub.B T, where k.sub.B is the Boltzmann constant and T is the operating temperature in kelvins, with said light holes having a lower energy than said heavy holes.
Dependencies are inferred from the claim text.