Study of SnO/ɛ-Ga2O3 p–n diodes in planar geometry

Abstract

SnO/[Formula: see text]-Ga2O3 vertical p–n diodes with planar geometry have been fabricated on c-plane Al2O3 and investigated by current–voltage measurements. The effects of the in-plane conduction through the Si-doped [Formula: see text]-Ga2O3 layer on the diode performance and their relevance have been evaluated. A significant series resistance is observed, which shows typical features of the variable range hopping transport observed in Si-doped [Formula: see text]-Ga2O3; this in-plane transport mechanism is probably induced by the columnar domain structure of this polymorph. The dependence of the series resistance on the geometry of the diode supports the interpretation. A simple equivalent model is presented to describe the experimental behavior of the diode, supported by preliminary impedance spectroscopy investigation.

Silane‐Mediated Expansion of Domains in Si‐Doped κ‐Ga2O3 Epitaxy and its Impact on the In‐Plane Electronic Conduction

“…[29] Nonetheless, the extrinsically doped layers suffered from a limited electron mobility (at room temperature µ ≈ 1 cm 2 V −1 s −1 ) due to a hopping transport mechanism. [28,29] As recently suggested by Kneiß et al [30] and some authors of this work, [31] this could be linked to the nanometric-sized rotational domains representing an effective barrier for the in-plane electronic conduction, i.e., a perturbation in the lateral crystal periodicity comparable to the electrons' mean free path. [29] Therefore, finding synthesis conditions that could at the same time allow the extrinsic doping of the material and a domain size control would represent a major step forward for the understanding of the real κ-Ga 2 O 3 intrinsic material properties, which is in turn fundamental for its breakthrough in the field of new generation electronic devices.…”

Interfacial Properties of the SnO/κ-Ga2O3 p-n Heterojunction: A Case of Subsurface Doping Density Reduction via Thermal Treatment in κ-Ga2O3

“…The adoption of the correct model associated with a given junction is extremely important, since an inappropriate choice can lead to the wrong determination of the carrier type . For instance, in the case of planar diodes, the series resistance given by the portion of material around the diode junction area has a high impact on the measurements and can drastically affect the estimate of the junction properties . The series resistance can influence the capacitance measurement, which itself can cause large errors in calculation of the doping profile, and built-in potential .…”

“…SnO resulted rather polycrystalline, with random in-plane orientation; then, lattice match does not seem to matter. Information about the XRD 2θ–ω scan of the SnO(001)/κ-Ga 2 O 3 diode under study is reported in the Supporting Information of ref , where also more details about the fabrication procedures of the SnO/κ-Ga 2 O 3 diode, its geometrical dimensions, and doping levels of the p- and n-type sides, independently investigated as single layers, are given . Further information about the result of room temperature Raman spectroscopy measurement of the SnO layer is given in the Supporting Information.…”

“…Many growth methods are available for epitaxial growth of Ga 2 O 3 polymorphs such as metal–organic chemical vapor deposition (MOCVD), , magnetron sputtering, , mist-chemical vapor deposition (Mist-CVD), , atomic layer deposition (ALD), , pulsed laser deposition (PLD), halide vapor phase epitaxy, and molecular beam epitaxy (MBE). , In spite of the numerous merits of the β-Ga 2 O 3 , there are concerns regarding its anisotropic thermal conductivity and easiness of cleavage. ,, κ-Ga 2 O 3 is the second most stable polymorph, and its orthorhombic cell has higher symmetry with respect to the monoclinic one, which may lead to easier epitaxial growth and novel heterostructures. , Furthermore, it exhibits a spontaneous polarization along the [001] direction of the orthorhombic cell that could help to obtain high-density two-dimensional electron gases (2DEG) at the interface of κ-Ga 2 O 3 based heterostructures, , and thus a conducting channel for high-mobility field effect transistors, which is becoming one of the most intriguing topics of the literature on Ga 2 O 3 . Recently, κ-Ga 2 O 3 , was employed for fabrication of planar diodes and solar-blind UV–C photodetectors . It must be noted that this polymorph, which indeed has an orthorhombic crystallographic lattice, is often named ε because it shows a pseudohexagonal structure when investigated by X-ray diffraction.…”

“…Therefore, to fabricate diodes, one has to develop suitable Schottky contacts or p–n heterojunctions. So far the study of Schottky diodes and p–n junctions in planar or vertical configuration, based on the orthorhombic Ga 2 O 3 , is very limited, considering either inorganic , or hybrid , junctions. Nowadays, heterojunctions of metal oxides and other materials such as perovskites or chalcogenides are becoming popular subjects of investigation…”