Polarity control and fabrication of lateral polarity structures of III-nitride thin films and devices: progress and prospects

Abstract

Due to their non-centrosymmetric crystal orientation, wurtzite III-nitride crystals have two distinct orientations, i.e. III-polar and N-polar along the c-axis. Extensive effort has been devoted to polarity control and the characterization of III-nitride thin films. Both III-polar and N-polar films possess some unique features. By taking full advantage of both III and N-polar domains in a single structure, a lateral polarity structure (LPS), where III-polar and N-polar domains are grown side-by-side simultaneously on the wafer, has attracted great interest. In this review, recent progress in the design and fabrication of III-nitride LPS on various substrates is summarized. The structural, optical and electronic properties of III-nitride thin films incorporating LPS are discussed, with special attention paid to the interface between adjacent domains. Various techniques to qualitatively and quantitatively identify the polarity domains are provided, and their applications in optoelectronic and electronic devices including light-emitting-diodes, nonlinear frequency doubling waveguides, Schottky-barrier-diodes, etc, are intensively elaborated on. Finally, challenges related to the development of LPS-based devices and future perspectives are presented.

Ultrasensitive UV-C detection based on MOCVD-grown highly crystalline ultrawide bandgap orthorhombic κ-Ga2O3

“…Highperformance UV-C PDs can also revolutionize the medical diagnosis, chemical/biological threat detection, sterilization process, etc. [5][6][7] Many efforts have been made to develop UV-C detectors using epitaxially grown group III-nitrides and oxide films [7][8][9]. These materials are stable at high temperatures and possess wide bandgap characteristics with wavelength tunability in the UV wavelength regime (200-400 nm).…”

On the polarity determination and polarity inversion in nitrogen-polar group III-nitride layers grown on SiC

“…For instance, III-nitride structures with lateral periodic metal-polar and N-polar domains have been used for second harmonic generation in compact tunable optical sources, for UV light emitting diodes (LED) with increased internal quantum efficiency, for Schottky barrier diodes with reduced on-resistance, and for novel threeterminal devices. [5][6][7][8][9][10] Notably, N-polar high electron mobility transistors (HEMTs) have emerged as very promising to expand device designs by offering improved scalability, reduced resistance of ohmic contacts, better confinement of the two-dimensional electron gas (2DEG), and better dynamic performance compared to metal-polar devices. [11][12][13][14][15] It has been shown that by varying growth temperature, V/III ratio, and surface pretreatment, either N-polar, metal-polar, or a mixed-polarity III-nitride layers can be realized.…”

Ultrasensitive Uv-C Detection Based on Mocvd-Grown Highly Crystalline Ultrawide Bandgap Orthorhombic Κ-Ga2o3

“…High-performance UV-C PDs can also revolutionize the medical diagnosis, chemical/biological threat detection, sterilization process, etc. [5][6][7] Many efforts have been made to develop UV-C detectors using epitaxially grown group III-nitrides and oxide films [7][8][9]. These materials are stable at high temperatures and possess wide bandgap characteristics with wavelength tunability in the UV wavelength regime (200 ~ 400 nm).…”