Absorption Saturation with Doping in p-QWIPs: Role of Continuum
Abstract
The design of the bound-to-continuum p-type GaAs/AlGaAs quantum well infrared photodetectors (p-QWIPs)requires the second light-hole (LH2) level to be in resonance with the top of the valence band QW. However, we found experimentally that such absorption can saturate as a function of doping in the well. This result can be explained on the basis of an envelope-function approximation calculation (EFA), which shows that the line of resonances in the continuum as a function of the in-plane wave vector can eventually become a bound LH2 band in the well at some critical wave vector. Therefore, moving the LH2 continuum resonance slightly deeper into the continuum can avoid absorption saturation and produce optimal p-QWIP response. This hypothesis was tested by growing and measuring the photoresponse of suitable mid-IR p-QWIPs. The measured photoresponse more than doubled through the use of the new p-QWIP design. Therefore, it is possible to avoid absorption saturation by matching this critical wave vector (i.e., well width and/or well depth) with the Fermi wave vector (i.e., doping in the well) for the desired QWIP (i.e., cutoff wavelength).
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2003
- Bibcode:
- 2003APS..MAR.D8005S