Adomian's decomposition method (ADM) is a nonnumerical method which can be adapted for solving nonlinear ordinary differential equations. In this paper, the principle of the decomposition method is described, and its advantages as well as drawbacks are discussed. Then an aftertreatment technique (AT) is proposed, which yields the analytic approximate solution with fast convergence rate and high accuracy through the application of Padé approximation to the series solution derived from ADM. Some concrete examples are also studied to show with numerical results how the AT works efficiently.

永昌 焦;Y. Yamamoto;C. Dang;跃 郝

Computers and Mathematics with Applications

2002-3

A combination of high maximum oscillation frequency (f_max) and breakdown voltage (V_br) was achieved in AlGaN/GaN high electron mobility transistors (HEMTs) with N₂O plasma treatment on the access region. The breakdown voltage is improved from 37 V to 80 V due to the formation of oxide layer in the gate region. A suppressed current collapse is obtained due to plasma treatment on the gate-source and the gate-drain regions. The effect of the present passivation method is almost the same with that of the conventional SiN passivation method, meanwhile it can avoid introducing additional parasitic capacitance due to thinner thickness. The small signal measurement shows that HEMT can yield f_T and f_max of 98 and 322 GHz, respectively, higher than that of 70 and 224 GHz for the non-treated HEMT. By using the plasma treatment technique, the HEMT can simultaneously exhibit high f_max and V_br with a record f_maxV_br of 25 THzV.

Min Han Mi;Xiao Hua Ma;Ling Yang;Yang Lu;Bin Hou;Meng Zhang;Heng Shuang Zhang;Sheng Wu;跃 郝

AIP Advances

2019-4-1

In this letter, the effects of the interface acceptor-like traps on the transient responses of AlGaN/GaN high-electron mobility transistors (HEMTs) are investigated by means of experimental measurements and numerical simulations. The variation trends of the drain current I_DS stimulated by the gate (V_GS) and drain (V_DS) turn-on voltage pulses have been analyzed. The successive numerical simulations are carried out on the test structure, into which a trapping region at the AlGaN/GaN interface is introduced. The same variation trends are observed on both of the simulated V_GS and V_DS turn-on pulse measurements. The observation proves that the interface acceptor-like trap is the factor dominating the turn-on transient response of the HEMT devices.

Wei Zhang;Yue Zhang;Wei Mao;Xiaohua Ma;进成 张;跃 郝

IEEE Electron Device Letters

2013

We report the amorphous Si passivation of Ge pMOSFETs fabricated on (001)-, (011)-, and (111)-orientated surfaces for advanced CMOS and thin film transistor applications. Amorphous Si passivation of Ge is carried out by magnetron sputtering at room temperature. With the fixed thickness of Si t _Si , (001)-oriented Ge pMOSFETs achieve the higher on-state current I _ON and effective hole mobility μ _eff compared to the devices on other orientations. At an inversion charge density Q _inv of 3.5 × 10 ¹² cm ⁻² , Ge(001) transistors with 0.9 nm t _Si demonstrate a peak μ _eff of 278 cm ² /V × s, which is 2.97 times higher than the Si universal mobility. With the decreasing of t _Si , I _ON of Ge transistors increases due to the reduction of capacitive effective thickness, but subthreshold swing and leakage floor characteristics are degraded attributed to the increasing of midgap D _it .

Huan Liu;根全 韩;Yan Liu;Xiaosheng Tang;Jingchen Yang;跃 郝

Nanoscale Research Letters

2019

GaNs grown by hydride vapor phase epitaxy (HVPE) were irradiated by protons with different fluences. The changes of surface topography of as-grown and irradiated samples were characterized by atomic force microscopy (AFM). The crystal quality and optical properties of GaN films were examined by the variations of the micro-Raman and photoluminescence (PL) spectra with proton fluence. It was observed that the surface became a little more rough after irradiation. The Raman spectra indicated that the strain of materials and carrier concentration were not affected by the proton injection. The full-width at half-maximum (FWHM) of E ₂ ^high phonon mode narrowed, which was consistent with the FWHM of PL near-band-edge emission (BE). The spectra of yellow luminescence and blue luminescence normalized to the intensity of BE demonstrated a little increase of Ga vacancy and a large decrease of O _N, which may be the main reason for the change of optical properties.

Ling Lü;跃 郝;Xue Feng Zheng;进成 张;Sheng Rui Xu;Zhi Yu Lin;Shan Ai;Fan Na Meng

Science China Technological Sciences

2012-9

The hot-carrier (HC) degradation of ultra-deep submicrometer lightly doped drain (LDD) metal oxide semiconductor field-effect transistors (MOSFET's) is studied in detail. A further experimental investigation of the two-stage HC degradation in 0.18μm LDD NMOSFET's is presented. The effects of degradation due to HC stress-induced defects in the oxide spacer and the gate-drain overlap/ channel regions separately during stress time are determined. The self-limiting HC degradation mechanism in ultra-deep submicrometer LDD NMOSFET's is proposed completely.

Chun Li Yu;跃 郝;林安 杨

2006

Step-stress experiments are performed in this paper to investigate the degradation mechanism of an AlGaN/GaN high electron mobility transistor (HEMT). It is found that the stress current shows a recoverable decrease during each voltage step and there is a critical voltage beyond which the stress current starts to increase sharply in our experiments. We postulate that defects may be randomly induced within the AlGaN barrier by the high electric field during each voltage step. But once the critical voltage is reached, the trap concentration will increase sharply due to the inverse piezoelectric effect. A leakage path may be introduced by excessive defect, and this may result in the permanent degradation of the AlGaN/GaN HEMT.

Wei Wei Chen;Xiao Hua Ma;Bin Hou;Jie Jie Zhu;进成 张;跃 郝

Chinese Physics B

2013-10

High quality InAlN/GaN heterostructures are successfully grown on the (0 0 0 1) sapphire substrate by pulsed metal organic chemical vapor deposition. The InAlN barrier layer with an indium composition of 17% is observed to be nearly lattice matched to GaN layer, and a smooth surface morphology can be obtained with root mean square roughness of 0.3 nm and without indium droplets and phase separation. The 50 mm InAlN/GaN heterostructure wafer exhibits a mobility of 1402 cm²/V s with a sheet carrier density of 2.01×10 ¹³ cm^-2, and a low average sheet resistance of 234 Ω/cm² with a sheet resistance nonuniformity of 1.22%. Compared with the conventional continual growth method, PMOCVD reduces the growth temperature of the InAlN layer and the Al related prereaction in the gas phase, and consequently enhances the surface migration, and improves the crystallization quality. Furthermore, indium concentration of InAlN layer can be controlled by adjusting the pulse time ratio of TMIn to TMAl in a unit cycle, the growth temperature and pressure, as well as the InAlN layer thickness by the number of unit cycle repeats.

Jun Shuai Xue;跃 郝;Xiao Wei Zhou;进成 张;Chuan Kai Yang;Xin Xiu Ou;Lin Yu Shi;Hao Wang;林安 杨;金风 张

Journal of Crystal Growth

2011-1-1

By measurement, we investigate the characteristics and location of gate oxide damage induced by snapback stress. The damage incurred during stress causes device degradation that follows an approximate power law with stress time. Oxide traps generated by stress will cause the increase of stress-induced leakage current and the decrease of Q_bd (charge to breakdown), and it may also cause the degradation of off-state drain leakage current. Stress-induced gate oxide damage is located not only in the drain side but also in the source side. The tertiary electrons generated by hot holes move toward Si-SiO₂ interface under the electrical field toward the substrate, which explains the source side gate oxide damage.

Zhiwei Zhu;跃 郝;Xiaohua Ma

Pan Tao Ti Hsueh Pao/Chinese Journal of Semiconductors

2007-3

Perovskite solar cells (PSCs) have been developed rapidly in recent years due to the excellent photoelectric properties and development potential. In this study, high performance and hysteresis-less planar structured perovskite (MA_1-yFA_yPbI_3-xCl_x) solar cell was successfully achieved via contact passivation of the compact titanium dioxide ("₂)/perovskite interface with NaCl doping method. It was found that the sodium chloride (NaCl) doping treatment on "₂ could significantly improve the electrical property of "₂ electron transport layer (ETL), and passivate the trap states at "₂/perovskite interface. Moreover, the improved interface contact between "₂ ETL and perovskite could efficiently enhance the charge transfer and suppress the charge recombination in the device. Hence, the power conversion efficiency (PCE) of PSC device based on NaCl-doped "₂ was enhanced to 18.3% compared with the pristine compact "₂-based PSCs (15.1%).

Jing Ma;Xing Guo;Long Zhou;Zhenhua Lin;Chunfu Zhang;Zhou Yang;Gang Lu;Jingjing Chang;跃 郝

ACS Applied Energy Materials

2018-8-27