Screening influence on the Stark effect of impurity states in strained wurtzite GaN/AlxGa1-xN heterojunctions under pressure
Zhang Min(张敏)a)b) and Ban Shi-Liang(班士良) a)†
a Department of Physics, School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China; b College of Physics and Electron Information, Inner Mongolia Normal University, Hohhot 010022, China
Abstract The screening effect of the random-phase-approximation on the states of shallow donor impurities in free strained wurtzite GaN/AlxGa1-xN heterojunctions under hydrostatic pressure and an external electric field is investigated by using a variational method and a simplified coherent potential approximation. The variations of Stark energy shift with electric field, impurity position, Al component and areal electron density are discussed. Our results show that the screening dramatically reduces both the blue and red shifts as well as the binding energies of impurity states. For a given impurity position, the change in binding energy is more sensitive to the increase in hydrostatic pressure in the presence of the screening effect than that in the absence of the screening effect. The weakening of the blue and red shifts, induced by the screening effect, strengthens gradually with the increase of electric field. Furthermore, the screening effect weakens the mixture crystal effect, thereby influencing the Stark effect. The screening effect strengthens the influence of energy band bending on binding energy due to the areal electron density.
Received: 22 August 2008
Revised: 13 August 2009
Accepted manuscript online:
PACS:
73.40.Kp
(III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions)
(Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect)
Fund: Project supported by the National
Natural Science Foundation of China (Grant No 60566002), and the
Specialized Research Fund for the Doctoral Program of Higher
Education of China (Grant No 20070126001).
Cite this article:
Zhang Min(张敏) and Ban Shi-Liang(班士良) Screening influence on the Stark effect of impurity states in strained wurtzite GaN/AlxGa1-xN heterojunctions under pressure 2009 Chin. Phys. B 18 5437
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