Control and Device Application of 2D Electrons and Holes in Polytype Heterostructures

Polytype heterostructures GaSb/InAs/AlGaSb have been grown by molecular beam epitaxy (MBE). We havestudied MBE growth conditions and process to obtain sharp heterointerfaces by the instantaneousshatter operations of molecular beams of III and V elements. In order to characterizeheterostructures grown by MBE，光学spectroscopy such as photoluminescence and Raman scattering and Hall measurements have beendone to optimize the detailed heterostructures for device applications.There is a trade off between过程feasibility and the electrical performance in the design of InAs/AlGaSb heterostructuresprocess feasibility requires lower aluminum content to avoid undesirable reactionwhile higher aluminum content是preferred for improved electrical characteristics. To meet both需要一个optimized heterostructure，我们有grown three类型InAs quantum well结构和compared electron transport properties。optimize InAs SQW structure with 60aaisb barrier has been fabricated for high speed FET. A1.7mum-gate-length FET with this optimized structure showed a very high transconductance of morethan 460ms /mm at room temperature. Higher transconductance and drain current increase in the highdrain voltage indicate the increased carrier concentration as observed by the pulsed Hallmeasurements.In order to control the distribution of electrons and holes near the InAs/AlGaSbinterface,我们有方法photoluminescence under an external electric field across the interface. Most ofelectrons and holes distribute separately in adjacent layers recombine to emit photons. Theblue-shift of the PL peak to higher energies has been observed for the first time with increasingexternal fields. This stark shift has been interpreted by the modulation of波函数electrons and holes，and also the shift of 2d energy states. This effect will be applicable for high speed opto-electricdevices。

Polytype heterostructures GaSb/InAs/AlGaSb have been grown by molecular beam epitaxy (MBE). We have studied MBE growth conditions and process to obtain sharp heterointerfaces by the instantaneous shatter operations of molecular beams of III and V elements. In order to characterize heterostructures grown by MBE, optical spectroscopy such as photoluminescence and Raman scattering and Hall measurements have been done to optimize the detailed heterostructures for device applications.There is a trade off between process feasibility and the electrical performance in the design of InAs/AlGaSb heterostructures ; process feasibility requires lower aluminum content to avoid undesirable reaction, while higher aluminum content is preferred for improved electrical characteristics. To meet both requirements for an optimized heterostructure, we have grown three typical InAs quantum well structures and compared electron transport properties. The optimize InAs SQW structure with 60AAISb barrier has been fabricated for high speed FET. A 1.7mum-gate-length FET with this optimized structure showed a very high transconductance of more than 460mS/mm at room temperature. Higher transconductance and drain current increase in the high drain voltage indicate the increased carrier concentration as observed by the pulsed Hall measurements.In order to control the distribution of electrons and holes near the InAs/AlGaSb interface, we have measured photoluminescence under an external electric field across the interface. Most of electrons and holes distribute separately in adjacent layers recombine to emit photons. The blue-shift of the PL peak to higher energies has been observed for the first time with increasing external fields. This stark shift has been interpreted by the modulation of wave functions of electrons and holes, and also the shift of 2D energy states. This effect will be applicable for highーspeed opto-electric devices.