Abstract
Capacitor and Schottky diode sensors were fabricated on GaN material grown by hydride vapor phase epitaxy and metal-organic chemical vapor deposition techniques using plasma etching and metal deposition. The operational characteristics of these devices have been investigated by profiling current transients and by comparing the experimental regimes of the perpendicular and parallel injection of excess carrier domains. Profiling of the carrier injection location allows for the separation of the bipolar and the monopolar charge drift components. Carrier mobility values attributed to the hydride vapor phase epitaxy (HVPE) GaN material have been estimated as μe = 1000 ± 200 cm2/Vs for electrons, and μh = 400 ± 80 cm2/Vs for holes, respectively. Current transients under injection of the localized and bulk packets of excess carriers have been examined in order to determine the surface charge formation and polarization effects.
Highlights
Gallium nitride (GaN) is a promising material for application in particle and photo-detectors, due to its high radiation hardness and relevant operational characteristics [1,2,3,4]
The long-tail non-exponential behavior of the microwave probed photo-conductivity (MW-PC) transients is caused by excess carrier trapping and de-trapping due to defects that are commonly introduced during metal-organic chemical vapor deposition (MOCVD) GaN crystal growth
MOCVD samples can be described by stretched-exponential relaxation (SER) [24,25], indicating the significant disorder induced by defects in the material
Summary
Gallium nitride (GaN) is a promising material for application in particle and photo-detectors, due to its high radiation hardness and relevant operational characteristics [1,2,3,4]. Preliminary GaN-based sensors have been developed and promising results have been recently reported [5,6]. The operational characteristics of detectors have been investigated by the transient current technique [5] using experimental regimes of perpendicular and parallel profiling. The experimental regimes of injection of the localized and bulk excess carrier packets have been examined in order to establish the surface charge formation and polarization effects [9,10,11]. The screening effects have been observed and ascribed to surface charge, and to dynamics of extraction of the injected excess carriers. The role of the injected carrier recombination and drift, as well as the impact of polarization effects, has been revealed
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