Detailed investigation of electron transport, capture and, gain in Al0.3Ga0.7As/GaAs quantum well infrared photodetectors


Cellek O., Besikci C.

SEMICONDUCTOR SCIENCE AND TECHNOLOGY, cilt.19, sa.2, ss.183-190, 2004 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 19 Sayı: 2
  • Basım Tarihi: 2004
  • Doi Numarası: 10.1088/0268-1242/19/2/010
  • Dergi Adı: SEMICONDUCTOR SCIENCE AND TECHNOLOGY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.183-190
  • Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

We present an investigation of Al0.3Ga0.7As/GaAs quantum well infrared photodetectors (QWIPs) through detailed ensemble Monte Carlo simulations. Both two-dimensional and three-dimensional electrons are simulated with realistically evaluated scattering rates. Transport of the excited electrons is accurately modelled including the reflections from well-barrier interfaces. The details incorporated into the simulator clarified some important phenomena, as well as verifying the previous predictions. Under large bias, well accumulation occurs non-uniformly, being highest near the emitter. Contrary to previous assumptions, the L valley is found to be the origin of a significant portion of the captured electrons even under typical bias voltages. Gamma-L transfer, while decreasing carrier mobility, also increases capture probability and decreases the electron lifetime, having a twofold effect on device gain. The above findings explain the large difference between the gains of AlxGa1-xAs/GaAs (with x similar to 0.3) and InP/In0.53Ga0.47As (or GaAs/InxGa1-xAs) QWIPs, as well as the bias dependence of gain. The average barrier electron velocity is close to the saturated electron velocity in bulk Al0.3Ga0.7As under moderate and large bias; however, low-field mobility is significantly lower than that in bulk material. While complementing previous work, our results offer a deeper understanding of some important QWIP characteristics by resolving the details of transport and electron dynamics in the device.