Applied Physics Express (APEX) is a letters journal devoted solely to rapid dissemination of up-to-date and concise reports on new findings in applied physics. It is published daily online and monthly for the printed version. The motto of APEX is high scientific quality and prompt publication. APEX is a sister journal of the Japanese Journal of Applied Physics (JJAP) and is published by IOP Publishing Ltd on behalf of the Japan Society of Applied Physics (JSAP).
This publication is partially supported by a Grant-in-Aid for Publication of Scientific Research Results from the Japan Society for the Promotion of Science.
From 2014, APEX will be published by IOP Publishing on behalf of The Japan Society of Applied Physics. All submissions and refereeing will continue to be handled by the APEX Editorial Office at The Japan Society of Applied Physics. To submit a paper to APEX, please connect to the editorial web site.
In the last 30 days
Shiro Kaneko et al 2014 Appl. Phys. Express 7 035102
Silicene or germanene is a monolayer honeycomb lattice made of Si or Ge, similar to graphene made of C. In this work, we have assessed the performance potentials of silicene nanoribbon (SiNR), germanene nanoribbon (GeNR), and graphene nanoribbon (GNR), which all have a sufficient band gap to switch off, as field-effect transistor (FET) channel materials. We have demonstrated that, by comparing at the same band gap of ∼0.5 eV, the GNR FET maintains an advantage over SiNR or GeNR FETs under an ideal transport situation, but SiNR and GeNR are attractive channel materials for high-performance FETs as well.
Yongzhen Wu et al 2014 Appl. Phys. Express 7 052301
A uniform and pinhole-free hole-blocking layer is necessary for high-performance perovskite-based thin-film solar cells. In this study, we investigated the effect of nanoscale pinholes in compact TiO 2 layers on the device performance. Surface morphology and film resistance studies show that TiO 2 compact layers fabricated using atomic layer deposition (ALD) contain a much lower density of nanoscale pinholes than layers obtained by spin coating and spray pyrolysis methods. The ALD-based TiO 2 layer acts as an efficient hole-blocking layer in perovskite solar cells; it offers a large shunt resistance and enables a high power conversion efficiency of 12.56%.
Witold Skowroński et al 2015 Appl. Phys. Express 8 053003
The perpendicular magnetic anisotropy of an Ir/CoFeB/MgO trilayer was investigated after annealing at temperatures ranging from 200 to 350 °C. In the trilayer system annealed at 300 °C, we measured an interface anisotropy energy of 1.9 mJ/m 2. Further annealing led to mixing of the buffer and ferromagnet, degrading the properties of the latter. In addition, we show the dependence of the magnetic anisotropy on the bias voltage. The presented system is important for the development of perpendicular magnetic tunnel junctions for storage applications.
Cyril Pernot et al 2010 Appl. Phys. Express 3 061004
We report on the fabrication and characterization of AlGaN-based deep ultraviolet light-emitting diodes (LEDs) with the emission wavelength ranging from 255 to 280 nm depending on the Al composition of the active region. The LEDs were flip-chip bonded and achieved external quantum efficiencies of over 3% for all investigated wavelengths. Under cw operation, an output power of more than 1 mW at 10 mA was demonstrated. A moth-eye structure was fabricated on the back side of the sapphire substrate, and on-wafer output power measurement indicated a 1.5-fold improvement of light extraction.
Tohru Oka et al 2015 Appl. Phys. Express 8 054101
In this paper, we report on 1.2-kV-class vertical GaN-based trench metal–oxide–semiconductor field-effect transistors (MOSFETs) on a free-standing GaN substrate with a low specific on-resistance. A redesigned epitaxial layer structure following our previous work with a regular hexagonal trench gate layout enables us to reduce the specific on-resistance to as low as 1.8 mΩ·cm 2 while obtaining a sufficient blocking voltage for 1.2-kV-class operation. Normally-off operation with a threshold voltage of 3.5 V is also demonstrated. To the best of our knowledge, this is the first report on vertical GaN-based MOSFETs with a specific on-resistance of less than 2 mΩ·cm 2.
Aiqin Tian et al 2015 Appl. Phys. Express 8 051001
Growth conditions were explored to suppress the carbon impurity incorporation in AlGaN:Mg grown at low temperatures. Electrical properties of Al 0.07Ga 0.93N:Mg samples with various carbon concentrations were investigated by Hall measurements. A clear correlation between carbon concentration and electrical conductivity has been found. By reducing the carbon concentration from 2 × 10 18 to 5 × 10 16 cm −3, the resistivity of p-Al 0.07Ga 0.93N decreases from 7.4 to 2.2 Ω·cm. From the results of the analysis of the charge neutrality equation, we found that the carbon concentration is close to the compensating donor concentration in the AlGaN:Mg samples, which suggests that carbon acts as the main compensating donor in AlGaN:Mg.
Takahiro Fukui et al 2014 Appl. Phys. Express 7 055201
Nitrogen-vacancy (NV) centers in diamond have attracted significant interest because of their excellent spin and optical characteristics for quantum information and metrology. To exploit these characteristics, precise control of the orientation of the NV axis in the lattice is essential. Here we show that the orientation of more than 99% of the NV centers can be aligned along the  axis by chemical vapor deposition homoepitaxial growth on (111) substrates. We also discuss the alignment mechanisms. Our result enables a fourfold improvement in the magnetic field sensitivity and opens new avenues to the optimum design of NV center devices.
Tomo-o Terasawa and Koichiro Saiki 2015 Appl. Phys. Express 8 035101
To obtain a large-area single-crystal graphene, chemical vapor deposition (CVD) growth on Cu is considered the most promising. Recently, the surface oxygen on Cu has been found to suppress the nucleation of graphene. However, the effect of oxygen in the vapor phase was not elucidated sufficiently. Here, we investigate the effect of O 2 partial pressure ( P O2) on the CVD growth of graphene using radiation-mode optical microscopy. The nucleation density of graphene decreases monotonically with P O2, while its growth rate reaches a maximum at a certain pressure. Our results indicate that P O2 is an important parameter to optimize in the CVD growth of graphene.
Imad Maouli et al 2015 Appl. Phys. Express 8 032401
The use of optical antennas in tip-enhanced Raman spectroscopy (TERS) makes it a powerful optical analysis and imaging technique at the nanoscale. Optical antennas can work as nano-light sources in the visible region. The plasmonic resonance of an antenna depends on its length; thus, by varying the length, one can control the enhancement in TERS. In this study, we demonstrated a fabrication method based on focused ion beam milling to realize optical antennas with desired lengths. We then measured the resonances of these fabricated antennas and performed TERS imaging of carbon nanotubes to demonstrate the antenna length dependence on plasmonic resonance.
Makoto Miyoshi et al 2015 Appl. Phys. Express 8 051003
Two-dimensional electron mobilities in AlGaN-channel nitride heterostructures were numerically and experimentally analyzed. The calculation and experimental results indicated that mobility for InAlN/AlGaN heterostructures grown by metalorganic chemical vapor deposition was limited by interface roughness scattering as well as alloy disorder scattering. The mobility limits for AlGaN-channel heterostructures with a two-dimensional electron gas (2DEG) density of 3 × 10 13/cm 2 were estimated to be, for instance, 249 cm 2 V −1 s −1 for an Al 0.3Ga 0.7N channel and 192 cm 2 V −1 s −1 for an Al 0.5Ga 0.5N channel. The calculated values showed no major disagreement with the results reported on AlGaN-channel heterostructures.
This cloud represents the 50 most popular PACS codes from the latest 250 coded articles for this journal. The larger the code the more times it occurs in those 250 articles. Click on a code to link to the articles in that category.
42.55.Px 42.65.Ky 42.55.Tv 42.15.Eq 07.57.Hm 06.30.Ft 42.60.Lh 42.65.Pc 42.30.Va 41.60.Cr 42.62.Cf 42.65.Tg 41.75.Fr 42.25.Gy 42.65.Jx 05.40.Ca 41.75.Jv 42.62.Be 42.55.Sa 42.30.Wb 42.25.Bs 33.50.Dq 07.60.Fs 07.55.-w 42.55.Rz 41.20.Jb 42.55.Wd 42.60.Jf 42.65.Re 24.60.Ky 31.15.ae 07.55.Db 42.25.Ja 07.50.Qx 07.07.Df 31.15.ej 42.55.Xi 07.57.Pt 42.30.Lr 29.20.dg 31.15.A- 42.65.Es 42.60.Da 29.25.Bx 07.55.Ge 07.85.Qe 42.40.Lx 42.55.Ye 42.50.Wk 42.50.Nn