1997 Fiscal Year Final Research Report Summary
Carrier Compensation Mechanism in Wide Bandgap II-VI Semiconductors
| Project/Area Number |
08455001
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | Tohoku University |
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Principal Investigator |
ZHU Zigiung TOHOKU University, Institute for Materials Research Research Associate, 金属材料研究所, 助手 (10243601)
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| Co-Investigator(Kenkyū-buntansha) |
LU Fang TOHOKU University, Institute for Materials Research, Research Associate, 金属材料研究所, 助手 (70281988)
YAO Takafumi TOHOKU University, Institute for Materials Research, Professor, 金属材料研究所, 教授 (60230182)
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| Project Period (FY) |
1996 – 1997
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| Keywords | II-VI Semiconductor / P-type ZnSe / Carrier Compensation Mechanism / Optical spectroscopy / Electrical Characterization / Ion Beam Analysis / Compensation Model / Energy Level Diagram for ZnSe : N |
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| Research Abstract |
There has been a lomg history of attempts to achieve reliable p-type wide bandgap II-VI semiconductors Park et al.and Ohkawa et al.were the first to successfully dope ZnSe grown by MBE using active nitrogen as a dopant and this important step led to the first demonstration of II-VI blue-green laser diodes. IIowever, the key issue remains how to achieve high conductivity p-type materials and pinpoints the mechanism of hole compensation. In this study, the identification and characterization of impurity levels in ZnSe : N have been extensively made by means of high resolution spectroscopy, photoluminescent excitation, selective photoluminescent excitation, deep level spectroscopy.
Over the past few years nitrogen has been found to be the best dopant in the production of p-type ZnSe by MBE.The mechanism of compensation appears to be the formation of this new type of donor center with a binding energy of 57meV.Evidence for the deep donor comes from the appearance of the DAP lines in the PL,
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spectra from ZnSe : N with a high N concentration. Additionally, a donor with a binding energy of 88meV and an acceptor with a binding energy of 170meV have been found in highly doped ZnSe : N through detailed optical studie. The energy lovel diagram has been proposed for N-doped ZnSe.
The caues of the compensation phenomenon have been attributed experimentally and theoretically to a number of origins : (i) compensation by native point defects (eg.a donor-type complex defect consisting of an N-acceptor and a selenium vacancy on a next nearest neighbor site (N_<Se>-Zn-V_<Se>) ; (ii) compensation by N clusters, for instance, a double donor consisting of a N acceptor and a N atom on adjacent Zn site (N_<Se>-N_<Zn>) ; (iii) compensation by N atoms at interstitial sites (N_<int>) ; and (iv) strong lattice relaxation. In addition, the nitrogen could form deep instead of shallow acceptors such as (N_<Se>-Zn-N_<Se>). The origins of the deep donor and acceptor centers found in the optical studies have been correlated to these N-associated complex defects and proposed. Less
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