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1. Doping and compensation in heavily Mg doped Al-rich AlGaN films

   https://doi.org/10.1063/5.0082992  

   Bagheri, Pegah; Klump, Andrew; Washiyama, Shun; Hayden Breckenridge, M.; Kim, Ji Hyun; Guan, Yan; Khachariya, Dolar; Quiñones-García, Cristyan; Sarkar, Biplab; Rathkanthiwar, Shashwat; et al (February 2022, Applied Physics Letters)

   Record low resistivities of 10 and 30 Ω cm and room-temperature free hole concentrations as high as 3 × 10¹⁸ cm⁻³were achieved in bulk doping of Mg in Al_0.6Ga_0.4N films grown on AlN single crystalline wafer and sapphire. The highly conductive films exhibited a low ionization energy of 50 meV and impurity band conduction. Both high Mg concentration (>2 × 10¹⁹cm⁻³) and low compensation were required to achieve impurity band conduction and high p-type conductivity. The formation of V_N-related compensators was actively suppressed by chemical potential control during the deposition process. This work overcomes previous limitations in p-type aluminum gallium nitride (p-AlGaN) and offers a technologically viable solution to high p-conductivity in AlGaN and AlN. 

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2. Control of passivation and compensation in Mg-doped GaN by defect quasi Fermi level control

   https://doi.org/10.1063/1.5126004  

   Klump, A.; Hoffmann, M. P.; Kaess, F.; Tweedie, J.; Reddy, P.; Kirste, R.; Sitar, Z.; Collazo, R. (January 2020, Journal of Applied Physics)
3. High Mg activation in implanted GaN by high temperature and ultrahigh pressure annealing

   https://doi.org/10.1063/5.0038628  

   Breckenridge, M. Hayden; Tweedie, James; Reddy, Pramod; Guan, Yan; Bagheri, Pegah; Szymanski, Dennis; Mita, Seiji; Sierakowski, Kacper; Boćkowski, Michał; Collazo, Ramon; et al (January 2021, Applied Physics Letters)

   null (Ed.)
4. Mg-related charge transitions in Mg-doped Ga2O3

   https://doi.org/10.1117/12.2582040  

   Bhandari, Suman; Zvanut, Mary E. (March 2021, SPIE 11687, Oxide-based Materials and Devices XII)

   Teherani, Ferechteh H.; Look, David C.; Rogers, David J. (Ed.)

   Gallium oxide (Ga2O3), an ultra-wide bandgap semiconductor with potential applications in power devices, may be doped with Mg to control the native n-type conductivity. The charge transitions associated with Mg in Mg-doped β-Ga2O3 crystals are studied using photoinduced electron paramagnetic resonance (photo-EPR) spectroscopy to understand the mechanisms that produce stable semi-insulating substrates. The steady state photo-EPR measurements are performed at 130 K by illuminating the samples with photon energy from 0.7 to 4.7 eV. Our results show that there are two transitions associated with Mg in the bandgap: onset of quenching of neutral Mg at 1.5 eV and excitation at 3.0 eV. The quenching threshold is consistent with several DFT predicted values for Mg-/0 level. Therefore, we suggest the quenching is due to transition of an electron from the valence band to the neutral Mg. For photoexcitation, hole capture is the only viable process due to polaronic nature of neutral Mg in Ga2O3. The measurements demonstrate that electron excitation to impurities, such as Fe and Ir, does not contribute to creation of the holes. Further, gallium vacancies must not participate since their characteristic EPR spectrum is never seen. Thus, we speculate that the defects responsible for the hole formation and consequent excitation of the neutral Mg are oxygen vacancies. 

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5. Strain-driven charge localization in lightly hole-doped manganite epitaxial films

   https://doi.org/10.1016/j.apsusc.2025.163145  

   Ryu, Sangkyun; Park, S-Y; Kim, Younghak; Nam, Sang-Yeol; Park, Jucheol; Hao, Lin; Liu, Jian; Cho, Jin H; Jeen, Hyoungjeen (August 2025, Applied Surface Science)