Impact Ionization Coefficient Prediction of a Lateral Power Device Using Deep Neural Network.

Nowadays, the impact ionization coefficient in the avalanche breakdown theory is obtained using 1-D PN junctions or SBDs, and is considered to be a constant determined by the material itself only. In this paper, the impact ionization coefficient of silicon in a 2D lateral power device is found to be no longer a constant, but instead a function of the 2D coupling effects. The impact ionization coefficient of silicon that considers the 2D depletion effects in real-world devices is proposed and extracted in this paper. The extracted impact ionization coefficient indicates that the conventional empirical impact ionization in the Fulop equation is not suitable for the analysis of 2D lateral power devices. The veracity of the proposed impact ionization coefficient is validated by the simulations obtained from TCAD tools. Considering the complexity of direct modeling, a new prediction method using deep neural networks is proposed. The prediction method demonstrates 97.67% accuracy for breakdown location prediction and less than 6% average error for the impact ionization coefficient prediction compared with the TCAD simulation.

Off-State Performance Characterization of an AlGaN/GaN Device via Artificial Neural Networks.

Due to the complexity of the 2D coupling effects in AlGaN/GaN HEMTs, the characterization of a device's off-state performance remains the main obstacle to exploring the device's breakdown characteristics. To predict the off-state performance of AlGaN/GaN HEMTs with efficiency and veracity, an artificial neural network-based methodology is proposed in this paper. Given the structure parameters, the off-state current−voltage (I−V) curve can therefore be obtained along with the essential performance index, such as breakdown voltage (BV) and saturation leakage current, without any physics domain requirement. The trained neural network is verified by the good agreement between predictions and simulated data. The proposed tool can achieve a low average error of the off-state I−V curve prediction (Ave. Error < 5%) and consumes less than 0.001‱ of average computing time than in TCAD simulation. Meanwhile, the convergence issue of TCAD simulation is avoided using the proposed method.

Extraction of Interface-Trap Densities of the Stacked Bonding Structure in 3D Integration Using High-Frequency Capacitance-Voltage Technique.

An extraction method of the interface-trap densities (Dit) of the stacked bonding structure in 3D integration using high-frequency capacitance-voltage technique is proposed. First, an accurate high-frequency capacitance-voltage model is derived. Next, by numerically solving the charge-balance equation and charge conservation equation, Dit is extracted by fitting the measured and calculated capacitance-voltage curves based on the derived model. Subsequently, the accuracy of the derived model is verified by the agreements between the analytical results and TCAD simulation results. The average extraction error proves the precision and efficiency of the extraction method. Finally, the stacked bonding structure has been fabricated, and Dit at the interface between silicon and insulator is extracted to diagnose and calibrate the fabrication processes.

A Novel Step-Doped Channel AlGaN/GaN HEMTs with Improved Breakdown Performance.

The AlGaN/GaN high electron mobility transistor with a step-doped channel (SDC-HEMT) is first proposed in this paper. The potential distribution and the electric field (E-field) distribution of the device are explored by the numerical approach and analytical approach simultaneously. By introducing extra dopants to the channel layer, the E-field distribution along the AlGaN/GaN heterojunction interface is reshaped, resulting in an improved breakdown characteristic. An optimized doping concentration gradient of channel layer of 2 × 1016 cm-3/step is proposed and verified by simulations. The breakdown voltage (BV) of the optimized SDC-HEMT reaches 1486 V with a 59.8% improvement compared with conventional AlGaN/GaN HEMT. In addition, the average E-field in the region between gate and drain improves from 1.5 to 2.5 MV/cm. Based on the equivalent potential method (EPM), an analytical model of the E-field and potential distribution is presented. The veracity and effectiveness of the proposed methodology is verified by the good agreement between the simulated and modeled results.

Prediction of Static Characteristic Parameters of an Insulated Gate Bipolar Transistor Using Artificial Neural Network.

Breakdown voltage (BV), on-state voltage (Von), static latch-up voltage (Vlu), static latch-up current density (Jlu), and threshold voltage (Vth), etc., are critical static characteristic parameters of an IGBT for researchers. Von and Vth can characterize the conduction capability of the device, while BV, Vlu, and Jlu can help designers analyze the safe operating area (SOA) of the device and its reliability. In this paper, we propose a multi-layer artificial neural network (ANN) framework to predict these characteristic parameters. The proposed scheme can accurately fit the relationship between structural parameters and static characteristic parameters. Given the structural parameters of the device, characteristic parameters can be generated accurately and efficiently. Compared with technology computer-aided design (TCAD) simulation, the average errors of our scheme for each characteristic parameter are within 8%, especially for BV and Vth, while the errors are controlled within 1%, and the evaluation speed is improved more than 107 times. In addition, since the prediction process is mathematically a matrix operation process, there is no convergence problem, which there is in a TCAD simulation.

Simulation Study of the Double-Gate Tunnel Field-Effect Transistor with Step Channel Thickness.

Double-gate tunnel field-effect transistor (DG TFET) is expected to extend the limitations of leakage current and subthreshold slope. However, it also suffers from the ambipolar behavior with the symmetrical source/drain architecture. To overcome the ambipolar current, asymmetry must be introduced between the source and drain. In this paper, we investigate the performances of DG TFET with step channel thickness (SC TFET) by utilizing the 2D simulation. The asymmetry between source and drain is introduced through the step channel thickness; hence, the ambipolar behavior is expected to be relieved. The results show that the SC TFET exhibits significant reduction of ambipolar current compared with the conventional DG TFET. The mechanisms of SC TFET are thoroughly discussed to explore the physical insight. The impacts introduced by the structure parameters on onset voltage, subthreshold slope, drain current in on-state and ambipolar-state are also exhibited in determining the optimal structure.

Prognostic factors in adult granulosa cell tumor of the ovary.

OBJECTIVE: To determine the clinicopathologic prognostic factors in adult granulosa cell tumors (GCTs) of the ovary. METHODS: This retrospective study was carried out over a period of 10 years (1995-2005) in the Gynecology Department of Shengjing Hospital, China Medical University, Shenyang, China. Forty-six patients with GCT were enrolled in this study. Demographic data, pathologic findings, treatments, and survival time were reviewed and analyzed for prognostic significance. RESULTS: It was found that International Federation of Gynecology and Obstetrics (FIGO) stage (p=0.0003), presence of nuclear atypia (p=0.036), and increased mitoses (p=0.002) were the 3 factors that impacted significantly on survival. Age, residual tumor disease, parity, and size of the tumor had no significant effect on survival. The only factor associated with risk of recurrence was rupture of the tumor (p=0.038). Patients who received chemotherapy had a better median disease-free survival than those who did not (105 versus 78 months), however, this did not reach statistical significance (p=0.080). CONCLUSION: The FIGO stage, nuclear atypia, and increased mitoses are the statistically significant prognostic factors, and may be used for selecting patients for adjuvant therapy. A prolonged follow-up is necessary due to risk of recurrences, late, and exceptional for the adult ovarian GCT, especially when the tumor ruptured before, or at operation.

Biphasic effects of orexin-A on autonomic nerve activity and lipolysis.

Previously, we showed that orexin-A, a 33-aa peptide, influences renal sympathetic nerve activity. Because the autonomic nervous system plays an important role in the regulation of lipid metabolism, we investigated the in vivo effects of orexin-A on the sympathetic nerve activity innervating white adipose tissue (WAT-SNA) and lipolysis. We found that intracerebroventricular (icv) administration of orexin-A at doses of 1 microg/rat and 10 ng/rat elevated and suppressed WAT-SNA, respectively. The effect of the high dose of orexin-A (1 microg/rat) was eliminated by pretreatment with diphenhydramine hydrochloride, a histamine H(1) receptor antagonist. In contrast, the effect of the low dose of orexin-A (10 ng/rat) was suppressed by thioperamide maleate salt, a histamine H(3) receptor antagonist. Moreover, icv administration of 1 microg/rat and 10 ng/rat of orexin-A increased and decreased the levels of plasma free fatty acids (FFAs), respectively. The effect of 1 microg/rat of orexin-A on plasma FFA was eliminated by propranolol hydrochloride, a beta-adrenergic receptor blocker, and also by diphenhydramine. The effect of orexin-A at dose of 10 ng/rat disappeared by pretreatment with atropine sulfate, a muscarinic receptor blocker, and thioperamide maleate salt. Our results suggest that high doses of orexin-A may regulate the lipolytic processes in adipose tissue through facilitation of the sympathetic nervous system, which is driven by histamine neurons through the H(1) receptor, and that the beta(3)-receptor may be involved in this enhanced lipolytic response. Low doses of orexin-A, on the other hand, may lower lipolysis by suppressing sympathetic nerve activity via the H(3)-receptor, and the muscarinic receptor may be related to this response.

Regulation of sympathetic nerve activity by L-carnosine in mammalian white adipose tissue.

Previously, we showed that l-carnosine, a bioactive dipeptide, influences the sympathetic nerve activity innervating kidney and brown adipose tissue. Because the autonomic nervous system plays an important role in the regulation of lipid metabolism, we investigated the in vivo effects of L-carnosine on the sympathetic nerve activity innervating white adipose tissue (SNA-WAT) and lipolysis. We found that intraperitoneal (ip) administration of L-carnosine at doses of 100 ng/rat and 10 microg/rat elevated and suppressed SNA-WAT, respectively. The effect of lower dose of L-carnosine (100 ng/rat) was eliminated by pretreatment with diphenhydramine hydrochloride, a histamine H(1) receptor antagonist. In contrast, the effect of higher dose of L-carnosine (10 microg/rat) was suppressed by thioperamide maleate salt, a histamine H(3) receptor antagonist. Moreover, ip administration of 100 ng and 10 microg of L-carnosine increased and decreased the levels of plasma free fatty acids (FFAs), respectively. The changes of plasma FFAs resulting from the exposure to 100 ng and 10 microg of L-carnosine were diminished by the beta-adrenergic receptor blocker propranolol hydrochloride and the muscarinic receptor blocker atropine sulfate, respectively; and eliminated by the corresponding histamine receptor antagonists, which eliminated the changes in SNA-WAT. Our results suggest that low doses of L-carnosine may regulate the lipolytic processes in adipose tissue through facilitation of the sympathetic nervous system, which is driven by histamine neurons through the H(1) receptor, and that the beta(3)-receptor may be involved in this enhanced lipolytic response. High doses of L-carnosine, on the other hand, may lower lipolysis by suppressing sympathetic nerve activity via the H(3) receptor, and the muscarinic receptor may be related to this response.

[Research development of catalytic-kinetic spectrophotometric determination of trace manganese].

A review of recent research progresses in the determination of trace amount of manganese with catalytic-kinetic spectrophotometric method is presented and discussed in the present paper. Firstly, by comparison it is showed that catalytic-kinetic spectrophotometry has more advantages than atomic absorption spectrophotometry and extraction-spectrophotometry for the determination of trace amounts of manganese. The review and discussion of the recent research developments in the catalytic discoloring spectrophotometry and catalytic coloring spectrophotometry for the determination of trace amounts of manganese are given respectively. Finally the development trends and application perspectives for the catalytic-kinetic spectrophotometry in the future are discussed and probed. Twenty five references are cited.

Expression of midkine in benign, premalignant and malignant vulvar tumors.

OBJECTIVE: To clarify the role of midkine (MK) in vulvar carcinogenesis though examination of its expression in vulvar lesions including vulvar condyloma acuminata (VCA), vulvar intraepithelial neoplasia (VIN) and vulvar squamous cell carcinomas (VSCC), and to analyze the relationship between MK expression and human papilloma virus (HPV) infection. METHODS: Thirty VSCC, 15 VIN and 10 VCA patients were studied by streptavidin-biotin-immunoperoxidase method. MK expression was compared with clinicopathologic features of vulvar tumors. RESULTS: MK was expressed in 26 of 30 VSCC (87%), 3 of 5 VIN III and all VCA samples, whereas no MK expression was detected in the VIN I-II samples or in normal epithelium. The difference of MK expression between VIN III and VSCC was statistically significant (P < 0.05). MK was more intensely expressed in differentiated-type (well differentiated and moderately differentiated) VSCC than in undifferentiated-type (poorly differentiated) VSCC. There was no statistically significant correlation between MK expression and clinical stage, lymph node metastasis and HPV infection in VSCC. MK expression were observed in all HPV-positive specimens including 2 VSCC, 1 VIN III and all VCA. CONCLUSIONS: MK gene expression may be a late event in vulvar squamous cell malignant transformation, and may be associated with vulvar tumor cell differentiation. HPV-positive vulvar tumors expressed MK protein.