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...

/pdf/luminescence-properties-of-defects-in-gan-4hjs241x7f.pdf

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

Impact of surface step heights of 6H–SiC (0 0 0 1) vicinal substrates in heteroepitaxial growth of 2H–AlN

Lattice parameters of high-dose ion-implanted 4H-SiC were investigated with reciprocal space mapping (RSM). N, P, Al, or (C+Si) ions were implanted into lightly doped epilayers to form a (330–520) nm-deep box profile with concentrations of 1019-1020atoms/cm3. After activation annealing at 1800 °C, RSM measurements were conducted. The RSM images for (0008) reflection revealed that high-dose ion implantation causes c-lattice expansion in implanted layers, irrespective of ion species. In addition, crystallographic tilt was observed after high-dose ion implantation. The tilt direction is the same for all the samples investigated; the c-axis of the implanted layers is inclined toward the ascending direction of the off-cut. The c-lattice mismatch and the tilt angle increased as the implantation dose increases, indicating that the implantation damage is responsible for the lattice parameter change. From these results and transmission electron microscopy observation, the authors conclude that the c-lattice mismat...

/pdf/lattice-mismatch-and-crystallographic-tilt-induced-by-high-2dh28anu0t.pdf

Lattice mismatch and crystallographic tilt induced by high-dose ion-implantation into 4H-SiC

The Hall scattering factor (γH) in p-type 4H-SiC with various aluminum doping concentrations of 5.8 × 1014–7.1 × 1018 cm−3 was investigated from 300 to 900 K. γH was determined by comparing the Hall coefficient with the theoretical carrier concentration derived from acceptor and donor concentrations obtained from secondary ion mass spectrometry and capacitance–voltage measurements. γH decreased with increasing temperature or doping concentration; γH = 1–0.4 for the doping concentration of 5.8 × 1014 cm−3 and γH = 0.5–0.2 for the doping concentration of 7.1 × 1018 cm−3. The dependence might be caused by the anisotropic and nonparabolic valence band structure of 4H-SiC.

https://iopscience.iop.org/article/10.7567/APEX.9.041301/pdf

Hall scattering factors in p-type 4H-SiC with various doping concentrations

Huge spiral crystals of potassium dichromate (K 2 Cr 2 O 7 ) have been found to grow three-dimensionally in a gelatin medium when gelatin containing K 2 Cr 2 O 7 was dried slowly in a test tube at a low temperature. These spirals were all right-handed, and their widths, axial pitches and lengths were 2–3 mm, 5–6 mm and 20–25 mm, respectively. When the gelatin concentration in the medium was decreased, ordinary platelike crystals were observed to grow, instead of the spiral crystals. To the best of our knowledge, inorganic compounds such as K 2 Cr 2 O 7 have so far not been reported to form such huge spiral crystals. It is conjectured that collagen molecules, which compose the gelatin medium and have right-handed triple helix structure lead to the growth of spiral crystals.

Spiral Crystal Growth of Potassium Dichromate in Gelatin

Zirconium diboride (ZrB2) has excellent properties as an electrically conductive substrate for nitride semiconductors. In this paper, the bulk growth of ZrB2 by a floating-zone method and some properties of ZrB2, together with a brief summary of heteroepitaxial growth of gallium nitride (GaN) by molecular beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOVPE), are presented. By optimizing the bulk growth conditions, a 20-mm-diameter ZrB2 single crystal was obtained. The cleavage direction of the ZrB2 (0001) substrate was confirmed to be parallel to [1120], which is parallel to that of GaN (0001). Epitaxial growth by both MBE and MOVPE was demonstrated. The grown n-type GaN/ZrB2 structure exhibited ohmic-like current–voltage behavior. These results indicate that ZrB2 has potential for application to the substrate for nitride semiconductors.

Jun Suda

Papers

Impact of surface step heights of 6H–SiC (0 0 0 1) vicinal substrates in heteroepitaxial growth of 2H–AlN

Lattice mismatch and crystallographic tilt induced by high-dose ion-implantation into 4H-SiC

Hall scattering factors in p-type 4H-SiC with various doping concentrations

Spiral Crystal Growth of Potassium Dichromate in Gelatin

ZrB2 Substrate for Nitride Semiconductors