Conditions for space-charge reversal at thermionic heterojunctions designed for ballistic electron injection

Semiconductor heterojunctions (HJs) have been used as injectors for ballistic electrons in high-speed devices. It was found that the charge state of the HJ has a significant influence on the ballistic-electron-injection process. The Al/sub x/FGa/sub 1-x/As/GaAs HJ was used as the demonstration system. A self-consistent ensemble Monte-Carlo formulation has been used in the quantitative calculations and simple model as an intuitive explanation. The state of the narrow-gap semiconductor can be changed from accumulation to depletion with one or several of the following: applied voltage, temperature, of Al mole fraction. The ballistic-electron fraction can vary by a factor of 3 depending on this space charge.<
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