In this paper, we present a 1.8-kV circular AlGaN/GaN/AlGaN double-heterostructure high electron mobility transistor(DH HEMT) with a gate-drain spacing L_(GD)= 18.8 μm. Compared with the regular DH HEMT, our circular...
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In this paper, we present a 1.8-kV circular AlGaN/GaN/AlGaN double-heterostructure high electron mobility transistor(DH HEMT) with a gate-drain spacing L_(GD)= 18.8 μm. Compared with the regular DH HEMT, our circular structure has a high average breakdown electric-field strength that increases from 0.42 MV/cm to 0.96 MV/cm. The power figure of meritV_(BR)~2/RON for the circular HEMT is as high as 1.03 ×10~9 V^2·Ω^(-1)·cm^(-2). The divergence of electric field lines at the gate edge and no edge effect account for the breakdown enhancement capability of the circular structure. Experiments and analysis indicate that the circular structure is an effective method to modulate the electric field.
The dependence of perpendicular magnetic anisotropy (PMA) on the barrier layer MgO thickness in MgO/CoFeB /Ta multilayers is investigated. The results show that the strongest PMA occurs in a small window of about 2 ...
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The dependence of perpendicular magnetic anisotropy (PMA) on the barrier layer MgO thickness in MgO/CoFeB /Ta multilayers is investigated. The results show that the strongest PMA occurs in a small window of about 2 4nm with the increase of MgO thickness from 1-1Onto. The crystalline degree of MgO and the change of interatomic distance along the out-of-plane direction may be the main reasons for the change of PMA in these multilayers. Moreover, the roughnesses of 2- and 4-nm-thick MgO samples are 3.163 and 1.8 nm, respectively, and both the samples show PMA. These results could be used to tune the magnetic characteristic of the ultra thin CoFeB film for future applications in perpendicular magnetic devices.
Crossbar array provides a cost-effective approach for achieving high-density integration of two-terminal functional devices. However, the "sneaking current problem", which can lead to read failure, is a severe chall...
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Crossbar array provides a cost-effective approach for achieving high-density integration of two-terminal functional devices. However, the "sneaking current problem", which can lead to read failure, is a severe challenge in crossbar arrays. To inhibit the sneaking current from unselected cells, the integration of individual selection devices is necessary. In this work, we report a novel TaOx-based selector exhibiting a trapezoidal band structure formed by tuning the concentration of defects in the oxide. Salient features such as a high current density (1 MA·cm^-2), high selectivity (5 × 10^4), low off-state current (-10 pA), robust endurance (〉10^10), self-compliance, and excellent uniformity were successfully achieved. The integrated one-selector one-resistor (1S1R) device exhibits high nonlinearity in the low resistance state (LRS), which is quite effective in solving the sneaking current issue.
A detailed study of the magnetic characterizations of the top structure MgO/CoFeB/Mo is *** samples show strong perpendicular magnetic anisotropy(PMA) when the thickness of CoFeB is 0.9 nm and 1.1 *** saturation mag...
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A detailed study of the magnetic characterizations of the top structure MgO/CoFeB/Mo is *** samples show strong perpendicular magnetic anisotropy(PMA) when the thickness of CoFeB is 0.9 nm and 1.1 *** saturation magnetic moment and interface anisotropy constant are 1566 emu/cm3 and 3.75 erg/cm2,*** magnetic dead layer(MDL) is about 0.23 nm in this ***,strong capping layer thickness dependence is also *** strong PMA of 1.1 nm CoFeB only exists in a Mo cap layer thickness window of 1.2-2 *** maintain PMA,the metal layer could not be too thin or thick in these *** oxidation and diffusion of the metal capping layer should be respectively responsibility for the degradation of PMA in these thin or thick metal capping layer samples.
The characteristics of 4H-SiC PiN diodes with a carbon-implanted drift layer was investigated and the reason of characteristics improvement was analyzed. The forward voltage drops of the diodes with carbonimplanted dr...
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The characteristics of 4H-SiC PiN diodes with a carbon-implanted drift layer was investigated and the reason of characteristics improvement was analyzed. The forward voltage drops of the diodes with carbonimplanted drift layer were around 3.3 V, which is lower than that of devices without carbon implantation, the specific-on resistance was decreased from 9.35 to 4.38 mΩcm^2 at 100 A/cm^2, and the reverse leakage current was also decreased. The influence of carbon incorporation in the Si C crystalline grids was studied by using deep-level transient spectroscopy(DLTS). The DLTS spectra revealed that the Z_(1/2) traps, which were regarded as the main lifetime limiting defects, were dramatically reduced. It is proposed that the reduction of Z_(1/2) traps can achieve longer carrier lifetime in the drift layer, which is beneficial to the performance of bipolar devices.
The strain effects of the Zn1-xMgxO substrate on the bands structure of wurtzite Nb-doped Zn O bulk materials have been investigated using fi rst-principles calculations based on density functional theory. Firstly, th...
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The strain effects of the Zn1-xMgxO substrate on the bands structure of wurtzite Nb-doped Zn O bulk materials have been investigated using fi rst-principles calculations based on density functional theory. Firstly, the band gap increases gradually with increasing Nb contents in unstrained Nb-doped Zn O, which is consistent with the experimental results. Secondly, the band gap decreases with increasing substrate stress in Nb-doped Zn O/Zn1-xMgxO. Splitting energies between HHB(Heavy Hole Band) and LHB(Light Hole Band), HHB and CSB(Crystal Splitting Band) in Zn0.9167Nb0.0833O/Zn1-xMgxO almost remain unchanged with increasing substrate stress, while decrease slightly in Zn0.875Nb0.125O/Zn1-xMgxO. In addition, detailed analysis of the strain effects on the effective masses of electron and hole in Nb-doped Zn O/Zn1-xMgxO is also given.
This work studied systemically the device characteristics when the OFETs' channels turn into hundreds of nm. Standard planar OFETs have been fabricated using electronic beam lithography. Copper phthalocyanine is u...
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High-resistivity β-Ga203 thin films were grown on Si-doped n-type conductive β-Ga203 single crystals by molecular beam epitaxy (MBE). Vertical-type Schottky diodes were fabricated, and the electrical properties of...
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High-resistivity β-Ga203 thin films were grown on Si-doped n-type conductive β-Ga203 single crystals by molecular beam epitaxy (MBE). Vertical-type Schottky diodes were fabricated, and the electrical properties of the Schottky diodes were studied in this letter. The ideality factor and the series resistance of the Schottky diodes were estimated to be about 1.4 and 4.6 x 10^6 %. The ionized donor concentration and the spreading voltage in the Schottky diodes region are about 4 x 10^18 cm-3 and 7.6 V, respectively. The ultra-violet (UV) photo-sensitivity of the Schottky diodes was demonstrated by a low-pressure mercury lamp illumination. A photoresponsivity of 1.8 A/W and an external quantum efficiency of 8.7 x 10%2% were observed at forward bias voltage of 3.8 V, the proper driving voltage of read-out integrated circuit for UV camera. The gain of the Schottky diode was attributed to the existence of a potential barrier in the i-n junction between the MBE-grown highly resistive β-Ga203 thin films and the n-type conductive β-Ga203 single-crystal substrate.
Oscillator is a common key component of electronic *** periodic signal produced by the oscillator is generally required in various applications,such as the electronic system clock,electronic neurons,and the true rando...
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Oscillator is a common key component of electronic *** periodic signal produced by the oscillator is generally required in various applications,such as the electronic system clock,electronic neurons,and the true random number generator system[1-6].Capacitors and inductors are usually utilized to generate periodic waveforms in the traditional oscillator,which greatly reduces integration and cannot be packaged into chips[2].Oscillators based on a memristor have been proposed as a solution to these issues[7-14].The memristor has attracted great attention and has been widely applied in many fields,such as memory,com?puting,security,etc.
The GHO (Gd2O3-doped HfO2) films were epitaxially grown on Ge (001) substrates adopting cube-on-cube mode with zero interface layer using pulsed laser deposition (PLD). Reflection high-energy electron diffracti...
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The GHO (Gd2O3-doped HfO2) films were epitaxially grown on Ge (001) substrates adopting cube-on-cube mode with zero interface layer using pulsed laser deposition (PLD). Reflection high-energy electron diffraction (RHEED) and high-resolution transmission electron microscopy (HRTEM) observation revealed a sharp interface of GHO/Ge and orientation relationship corre-sponding to (001)GHO//(001)Ge and [011] GHO//[011]Ge. The band offset for GHO/Ge stack was evaluated to be 3.92 eV for va-lence band and 1.38 eV for conduction band by X-ray photoelectron spectrum. Small equivalent oxide thickness (0.49 nm) and inter-face state density (7×1011 cm-2) were achieved from Au/Ti/GHO/Ge/Al capacitors.
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