Contactless doping characterization of Ga2O3 using acceptor Cd probes


Finding suitable p-type dopants, as well as reliable doping and characterization methods for the emerging wide bandgap semiconductor beta-Ga2O3 could strongly influence and contribute to the development of the next generation of power electronics. In this work, we combine easily accessible ion implantation, diffusion and nuclear transmutation methods to properly incorporate the Cd dopant into the beta-Ga2O3 lattice, being subsequently characterized at the atomic scale with the Perturbed Angular Correlation (PAC) technique and Density Functional Theory (DFT) simulations. The acceptor character of Cd in beta-Ga2O3 is demonstrated, with Cd sitting in the octahedral Ga site having a negative charge state, showing no evidence of polaron deformations nor extra point defects nearby. The possibility to determine the charge state of Cd will allow assessing the doping type, in particular proving p-type character, without the need for ohmic contacts. Furthermore, a possible approach for contactless charge mobility studies is demonstrated, revealing thermally activated free electrons for temperatures above similar to 648 K with an activation energy of 0.54(1) and local electron transport dominated by a tunneling process between defect levels and the Cd probes at lower temperatures.



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Science & Technology - Other Topics


Barbosa, MB; Correia, JG; Lorenz, K; Lopes, AML; Oliveira, GNP; Fenta, AS; Schell, J; Teixeira, R; Nogales, E; Mendez, B; Stroppa, A; Araujo, JP

our authors


This work was performed within the ISOLDE proposal IS481 and supported by FCT-Portugal, projects CERN-FP-123585-2011, CERN-FIS-PAR-0005-2017, CERN/FIS-TEC/0003/2019, POCI-01-0145-FEDER-032527 and PTDC/CTM-CTM/3553/2020, and by the European Commission through FP7- ENSAR (contract 262010) and Horizon 2020 program ENSAR2 (contract 654002). M. B. B. acknowledges a scholarship from FCT, SFRH/BD/97591/2013, J. S. a grant from the Federal Ministry of Education and Research (BMBF), 05K16PGA. The authors further acknowledge E. G. Villora and K. Shimamura (NIMS, Japan) for supplying the single crystal samples, the ISOLDE-CERN collaboration for supportive access to beam time and PD Reiner Vianden and the BONIS team at HISKP (Bonn, Germany) for the Cd implantations used for preliminary tests.

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