Gallium nitride (GaN) and its allied binaries InN and AIN as well as their ternary compounds have gained an unprecedented attention due to their wide-ranging applications encompassing green, blue, violet, and ultraviolet (UV) emitters and detectors (in photon ranges inaccessible by other semiconductors) and high-power amplifiers. However, even the best of the three binaries, GaN, contains many structural and point defects caused to a large extent by lattice and stacking mismatch with substrates. These defects notably affect the electrical and optical properties of the host material and can seriously degrade the performance and reliability of devices made based on these nitride semiconductors. Even though GaN broke the long-standing paradigm that high density of dislocations precludes acceptable device performance, point defects have taken the center stage as they exacerbate efforts to increase the efficiency of emitters, increase laser operation lifetime, and lead to anomalies in electronic devices. The p...

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Luminescence properties of defects in GaN

Wide bandgap semiconductors show superior material properties enabling potential power device operation at higher temperatures, voltages, and switching speeds than current Si technology. As a result, a new generation of power devices is being developed for power converter applications in which traditional Si power devices show limited operation. The use of these new power semiconductor devices will allow both an important improvement in the performance of existing power converters and the development of new power converters, accounting for an increase in the efficiency of the electric energy transformations and a more rational use of the electric energy. At present, SiC and GaN are the more promising semiconductor materials for these new power devices as a consequence of their outstanding properties, commercial availability of starting material, and maturity of their technological processes. This paper presents a review of recent progresses in the development of SiC- and GaN-based power semiconductor devices together with an overall view of the state of the art of this new device generation.

A Survey of Wide Bandgap Power Semiconductor Devices

An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

and Perspectives Sophie Carenco,†,‡,§,∥,⊥ David Portehault,*,†,‡,§ Ced́ric Boissier̀e,†,‡,§ Nicolas Meźailles, and Cleḿent Sanchez*,†,‡,§ †Chimie de la Matier̀e Condenseé de Paris, UPMC Univ Paris 06, UMR 7574, Colleg̀e de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France ‡Chimie de la Matier̀e Condenseé de Paris, CNRS, UMR 77574, Colleg̀e de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France Chimie de la Matier̀e Condenseé de Paris, Colleg̀e de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France Laboratory Heteroelements and Coordination, Chemistry Department, Ecole Polytechnique, CNRS-UMR 7653, Palaiseau, France

Nanoscaled metal borides and phosphides: recent developments and perspectives

Silicon carbide (SiC) power devices have been investigated extensively in the past two decades, and there are many devices commercially available now. Owing to the intrinsic material advantages of SiC over silicon (Si), SiC power devices can operate at higher voltage, higher switching frequency, and higher temperature. This paper reviews the technology progress of SiC power devices and their emerging applications. The design challenges and future trends are summarized at the end of the paper.

https://ieeexplore.ieee.org/ielaam/41/8031005/7815312-aam.pdf

Review of Silicon Carbide Power Devices and Their Applications

The Z1/2 center (EC - 0.67 eV), which is a lifetime killer in n-type 4H-SiC epilayers, is reduced by thermal oxidation. The oxidation, however, simultaneously generates other deep levels: ON1 (EC - 0.84 eV) and ON2 (EC - 1.1 eV) centers. From the behaviors (generation condition, thermal stability, and change in the depth profiles) of the ON1 and ON2 centers in samples (i) oxidized in O2, (ii) implanted with C+ or Si+ atoms, and (iii) oxidized in N2O (or NO), we suggest that these defects may originate from the same defect in different charge states, related to both carbon interstitials and N atoms.

https://iopscience.iop.org/article/10.7567/APEX.6.051301/pdf

Deep Levels Generated by Thermal Oxidation in n-Type 4H-SiC

We demonstrate 4H-SiC bipolar junction transistors (BJTs) with record current gains. Improved current gain was achieved by utilizing optimized device geometry as well as optimized surface passivation and continuous epitaxial growth of the emitter-base junction, combined with an intentional deep-level-reduction process based on thermal oxidation to improve the lifetime in p-SiC base. Current gain (β) of 257 was achieved for 4H-SiC BJTs fabricated on the (0001)Si-face. The gain of 257 is twice as large as the previous record gain. We also demonstrate, for the first time, BJTs on the (000–1)C-face that showed the highest β of 335 among the SiC BJTs ever reported.

4H-SiC bipolar junction transistors with record current gains of 257 on (0001) and 335 on (000–1)

The first-order Raman spectra of internal A1 and external modes in sintered hexagonal GeO 2 crystalline were measured in the temperature range of 293–873 K and the linewidths at these temperatures were obtained. The temperature dependence of the linewidths was analyzed using the phonon dispersion curves calculated on the basis of a rigid-ion model, and the results showed that it was caused approximately by the cubic anharmonic term in the crystal potential energy.

Lattice Dynamics and Temperature Dependence of the Linewidth of the First-Order Raman Spectra for Sintered Hexagonal GeO 2 Crystalline

The phonon-dispersion relations of LaAlO3 crystal are calculated using the first-principle calculations. The first-order Raman spectra in the LaGaO3 were measured in the temperature range of 20–300K for the rhombohedral phase. The temperature dependence of the linewidth of the Alg (132 cm-1) and that of Eg (489 cm-1) were analyzed using temperature-weighted two-phonon density of states (TDOS) due to the cubic term. The calculated results reproduce the observed ones in this temperature range. The scattering of a thermal phonon by observed phonons dominates phonon-phonon interaction on the rotational modes [the Alg (132 cm-1)]. Phonon-phonon interaction on the bending mode [the Eg (489 cm-1)] is dominated by both the scattering and the decay of the observed phonons into two phonons having lower energies. We found that this originates in the discrete spectra on the higher-frequency side in the phonon density of states that produces a difference in anharmonic effects on each peak's channels in the HT. This result is similar to that in the high-temperature phase in the case of LaGaO3 [1].

https://iopscience.iop.org/article/10.1088/1742-6596/150/5/052249/pdf

Anharmonicity on Raman active phonon modes of LaAlO3

We investigated surface passivation on 4H-SiC epitaxial layers with deposited or thermally grown SiO2 followed by POCl3 annealing. The measured carrier lifetime in a p-type epilayer with deposited SiO2 was limited to 0.5 µs and it was improved to 3.0 µs after POCl3 annealing. In an n-type epilayer, a measured carrier lifetime of 5.8 µs was improved to 12 µs after POCl3 annealing. We found a clear relationship between the measured carrier lifetime and the interface state density at SiO2/n-SiC after POCl3 annealing, suggesting that the reduction in interface state density lowered the surface recombination velocity on the 4H-SiC.

https://iopscience.iop.org/article/10.7567/APEX.9.051301/pdf

Jun Suda

Papers

Deep Levels Generated by Thermal Oxidation in n-Type 4H-SiC

4H-SiC bipolar junction transistors with record current gains of 257 on (0001) and 335 on (000–1)

Lattice Dynamics and Temperature Dependence of the Linewidth of the First-Order Raman Spectra for Sintered Hexagonal GeO 2 Crystalline

Anharmonicity on Raman active phonon modes of LaAlO3

Surface passivation on 4H-SiC epitaxial layers by SiO2 with POCl3 annealing