On the origin of the turn-on voltage drop of GaN-based current aperture vertical electron transistors

Non-linear output characteristics and the related turn-on voltages of GaN-based current aperture vertical electron transistors (CAVETs) are investigated experimentally. The resistive components are systematically analyzed in dependence of the device layout to determine the dominant resistances in th...

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Bibliographic Details
Published in:Journal of applied physics 2022-03, Vol.131 (11)
Main Authors: Döring, Philipp, Sinnwell, Matthias, Reiner, Richard, Driad, Rachid, Waltereit, Patrick, Leone, Stefano, Müller, Stefan, Mikulla, Michael, Ambacher, Oliver
Format: Article
Language:English
Subjects:
Activation energy
Apertures
Capacitance
Carrier density
Charge density
Charge transport
Current voltage characteristics
Drift
Electronic devices
Gallium nitrides
Interfacial properties
Potential barriers
Semiconductor devices
Space charge
Temperature dependence
Thermionic emission
Transistors
Voltage drop
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Summary:Non-linear output characteristics and the related turn-on voltages of GaN-based current aperture vertical electron transistors (CAVETs) are investigated experimentally. The resistive components are systematically analyzed in dependence of the device layout to determine the dominant resistances in the devices. Current–voltage (IV) and capacitance–voltage-characteristics (CV) are compared to a proposed planar-doped barrier diode (PDBD) model, and the influence of the bound sheet charge density and drift layer carrier concentration is discussed. The observed CV characteristics are in contrast to the PDBD model as a clearly voltage-dependent capacitance was observed and dopant-diffusion forming a p-type aperture was ruled out. Thermionic emission was verified by temperature-dependent IV characteristics indicating interface states causing a potential barrier. Transient drain current measurements revealed a single dominating trap level with an activation energy of EA = 1.086 ± 0.015 eV. This activation energy was attributed to carbon-related acceptor states present at the regrowth interface and the drift layer. Additional test structures revealed that the interface potential barrier and the space charge in the drift layer limit the initial charge transport causing a turn-on voltage in the devices. The results point out the significance of a precise control of the regrowth interface properties and the effective carrier density in the drift layer to enable efficient, high-power devices based on the CAVET technology.
ISSN:0021-8979
1089-7550
DOI:10.1063/5.0079760