Thermal Hysteresis Loop, Dynamical Breakdown, and Emission-Current Spike in Quantum-Well Photodetectors
Abstract
A nonadiabatic sequential-tunneling model is developed and applied to explore the common origin of the transient behavior of electrons in quantum-well photodetectors in the presence of different time-dependent external sources, including device temperature, electric field, and incident optical flux. For the time-dependent temperature, a counterclockwise hysteresis loop in the tunneling current as a function of the swept temperature is predicted and attributed to a blockade or an enhancement of the sequential tunneling of electrons between quantum wells by the space-charge-field effect when the device temperature is swept up and then down. When a time-dependent electric field is applied, a dynamical breakdown of the photodetectors is predicted, where the peak of total current linearly increases with the frequency of an ac electric field from its static value under a dc field. This is due to the presence of an additional dielectric current, which is proportional to the oscillation frequency of the ac electric field and whose peak value becomes larger than the value of the saturated tunneling-current peak in the high-frequency domain. Under the dynamical-breakdown condition, the quantum-well photodetectors behave just like a uniform dielectric medium. In the presence of a time-dependent optical flux, an emission-current spike is predicted as a result of the dominant enhancement of the escape probability of electrons from quantum wells over the loss of electron density when an applied dc electric field is small. The experimental observations of the transient behavior of electrons in quantum-well photodetectors are successfully reproduced by these numerical calculations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 15, 2001
- Accession Number
- ADA429634
Entities
People
- Anjali Singh
- Christian Morath
- D. A. Cardimona
- Danhong Huang
Organizations
- Air Force Research Laboratory