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Methods for point defect reduction in AlGaN (Conference Presentation)
Author(s): Ramon Collazo; Pramod Reddy; Shun Washiyama; Felix Kaess; Ronny Kirste; Seiji Mita; James Tweedie; Zlatko Sitar
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Paper Abstract

Defect incorporation in AlGaN is dependent on the defect formation energy and hence on associated chemical potentials and the Fermi level. For example, the formation energy of CN in Al/GaN varies as chemical potential difference (µN- µC) and -EF (Fermi level). Here, we demonstrate a systematic point defect control by employing the defect formation energy as tool by (a) chemical potential control and (b) Fermi level control. Chemical potential control (µN and µC) with a case study of C in MOCVD GaN is reported. We derive a relationship between growth parameters, metal supersaturation (i.e. input and equilibrium partial pressures) and chemical potentials of III/N and impurity atoms demonstrating successful quantitative predictions of C incorporation as a function of growth conditions in GaN. Hence growth environment necessary for minimal C incorporation within any specified constraints may be determined and C is shown to be controlled from >1E19cm-3 to ~1E15 cm-3. Fermi level control based point defect reduction is demonstrated by modifying the Fermi level describing the probability of the defect level being occupied/unoccupied i.e. defect quasi Fermi level (DQFL). The DQFL is modified by introducing excess minority carriers (by above bandgap illumination). A predictable (and significant) reduction in compensating point defects (CN, H, VN) in (Si, Mg) doped AlGaN measured by electrical measurements, photoluminescence and secondary ion mass spectroscopy (SIMS) provides experimental corroboration. Further, experiments with varying steady state minority carrier densities at constant illumination prove the role of minority carriers and DQFL in defect reduction over other influences of illumination that are kept constant.

Paper Details

Date Published: 14 March 2018
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Proc. SPIE 10532, Gallium Nitride Materials and Devices XIII, 1053209 (14 March 2018); doi: 10.1117/12.2291937
Show Author Affiliations
Ramon Collazo, North Carolina State Univ. (United States)
Pramod Reddy, North Carolina State Univ. (United States)
Adroit Materials, Inc. (United States)
Shun Washiyama, North Carolina State Univ. (United States)
Felix Kaess, North Carolina State Univ. (United States)
Ronny Kirste, North Carolina State Univ. (United States)
Adroit Materials, Inc. (United States)
Seiji Mita, North Carolina State Univ. (United States)
Adroit Materials, Inc. (United States)
James Tweedie, North Carolina State Univ. (United States)
Adroit Materials, Inc. (United States)
Zlatko Sitar, North Carolina State Univ. (United States)


Published in SPIE Proceedings Vol. 10532:
Gallium Nitride Materials and Devices XIII
Jen-Inn Chyi; Hiroshi Fujioka; Hadis Morkoç, Editor(s)

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