Разработка технологического процесса изготовления опоры двигателя

Выпускная квалификационная работа состоит из 4 разделов. В качестве задания был получен чертёж детали для которой разработан технологический маршрут изготовления. В технологическом разделе даны расчёты и пояснения для обеспечения требований, заданных конструктором. В качестве заготовки выбран круглый прокат алюминиевого сплава Д16Т. В конструкторском разделе спроектировано приспособления для сверления отверстий. В экономическом разделе выполнения расчёт стоимости детали. В разделе социальной ответственности и безопасности жизнедеятельности приведены основные требования для безопасной работы оператора за станком.This work is devoted to creation of technological process of the part "engine bracket" and consist of 4 parts. The first part is considering sequence of machining workpiece, calculation of operational time and cutting conditions. The second part is devoted to special device, which helps drilling accurate holes. The third and the forth parts are economical (where counting of the price is making) and social responsibility (where norms of pollution for workers and environment are calculated)

Performance of AlGaN/GaN Heterostructure Field-Effect Transistors for High-Frequency and High-Power Electronics

Preparation and properties of GaN-based heterostructure field-effect transistors (HFETs) for high-frequency and high-power applications are studied in this work. Performance of unpassivated and SiO2 passivated AlGaN/GaN HFETs, as well as passivated SiO2/AlGaN/GaN MOSHFETs (metal-oxide-semicondutor HFETs) is compared. It is found that MOSHFETs exhibit better DC and RF properties than simple HFET counterparts. Deposited SiO2 yielded an increase of the sheet carrier density from 7.6x10^12 cm^-2 to 9.2x10^12 cm^-2 and subsequent increase of the static drain saturation current from 0.75 A/mm to 1.09 A/mm. Small-signal RF characterisation of MOSHFETs showed an extrinsic current gain cut-off frequency fT of 24 GHz and a maximum frequency of oscillation fmax of 40 GHz. These are fully comparable values with state-of-the-art AlGaN/GaN HFETs. Finnaůůy, microwave power measurements confirmed excellent performance of MOSHFETs:the output power measured at 7 GHz is about two-times larger than that of simple unpassived HFET. Thus, a great potential in application of GaN-based MOSHFETs is documented. <br /

Output Power Improvement in MSM Photomixers by Modified Finger Contacts Configuration

A novel type of metal-semiconductor-metal (MSM) photomixers (PMs) with an improvement of output power and frequency bandwidth was fabricated and tested. The device active area with interdigitated MSM structure is divided into two smaller ones connected in series ("twin" configuration) and thus the capacitance is reduced by factor four while the responsivity is reduced only by factor two compared to the standard MSM design with the same area. This was verified by responsivity and transient photoresponse measurements on low-temperature-grown GaAs devices. The photomixing measurements yielded (2-3)-times higher output power of the twin PM than the power of the standard one in the whole frequency range from 200 GHz to 1.2 THz, which is in agreement with the calculations

Hybrid Optoelectronics Based on a Nanocrystal/III-N Nano-LED Platform

We fabricated and tested hybrid-III-nitride (CdSe nanocrystal/p-GaN/MQW/n-GaN/sapphire) based nano-LEDs and integrated them into a device layout suitable for DC testing and designed for future operation at high frequencies. Our studies provide clear evidence that our technological process for the vertically integrated nano-LED emitters is perfectly suited for long-term operation without any indication of degradation effects. This novel technology shows strong potential for a future single photon based OE circuit

Electrical and structural characterization of AlGaN/GaN field-effect transistors with recessed gate

Performance of AlGaN/GaN heterostructure field-effect transistors (HFETs) with recessed gate was investigated and compared with non-recessed counterparts. Optimal dry etch conditions by plasma assisted Ar sputtering were found for ~6 nm gate recess of a 20 nm thick AlGaN barrier layer. A decrease of the residual strain after the gate recessing (from -0.9 GPa to -0.68 GPa) was evaluated from the photoluminescence measurement. The saturation drain current at the gate voltage VG = 1 V decreased from 1.05 A/mm to 0.85 A/mm after the recessing. The gate voltage for a maximal transconductance (240-250 mS/mm) has shifted from -3 V for non-recessed HFETs to -0.2 V for recessed counterparts. Similarly, the threshold voltage increased after the gate recessing. A decrease of the sheet charge density from 1 x 10 13 cm-2 to4 x 10 12 cm-2 at VG = 0 V has been evaluated from the capacitance measurements. The RF measurements yielded a slight increase of the cut-off frequencies after the gate recessing. All these indicate that the gate recessing is a useful tool to optimize the AlGaN/GaN HFET performance for high-frequency applications as well as for the preparation of normally-off devices

Thermal Simulation of and Characterization of AlGaN/GaN/Si High Electron Mobility Transistors

28th international seminar on electronics technology, May 19-20, 2005We study the self-heating effect in a high-power AlGaN/GaN High Electron Mobility Transistor (HEMT) grown on silicon. We determine the HEMT static channel temperature using a dc characterization method and the results are compared with values calculated with a two-dimensional thermal model. No experimental data on the dynamic thermal behavior are available until now. For this reason, the transient thermal response on current pulses in the sub-microsecond range is estimated theoretically by means of a three-dimensional thermal model.Energie-Umweltmanagemen

Finite element simulation of metal-semiconductor-metal photodetector

The successful application of finite element analysis to ultrafast optoelectronic devices is demonstrated. Finite element models have been developed for both an alloyed- and surface-contact metal-semiconductor-metal photodetectors. The simulation results agree with previously reported experimental data. The alloyed device, despite having a somewhat larger capacitance, has a non-illuminated region of lower resistance with a more-uniform and deeper-penetrating electric field and carrier transport current. The latter explains, in terms of the equivalent lumped parameters, the experimentally observed faster response of the alloyed device. The model is further used to predict improved responsivity, based on electrode spacing and antireflective coating. We project that increasing the depth of the alloyed contact beyond approximately half of the optical penetration depth will not yield significantly improved responsivity. (C) 2009 Elsevier Ltd. All rights reserved

Tuning III-nitride nano-LEDs via laser-micro-annealing

Conventional reactive ion etching (RIE) used for the space definition/formation of nano-LEDs leads to a significant decrease in their electroluminescence. Among all the technological approaches to boost the efficiency of micrometer and nano- sized LED structures, the precise local laser micro annealing (LMA) procedure exhibits still undiscovered potential. The main goal behind the application of the “LMA” procedure is to “adjust” and/or to “engineer” the emission intensity of nano-LEDs according to requirements for example in transmistor based optical computing architectures currently under development. Here in this work, we present correlative ̶ optical (micro electro- & photoluminescence, Raman spectroscopy) and electrical ̶ characterization of single nano-LEDs in arrays integrated into a vertical device layout. Scanning electron microscopy investigations (figure 1) reveal inhomogeneous surface nano-LED morphology. Micro photoluminescence studies indicate that the LMA process has a direct impact on the curing of etching related defects. These are responsible for the suppression of radiative recombination in the nano-LED devices. Figure 2 presents a micro electroluminescence mapping after the successful “conditioning” procedure performed on nano-LEDs in an array with different annealing conditions. Furthermore, micro-Raman thermography investigations performed on single nano-LED structures (after LMA) disclose an up to 60K decrease in work temperature. Additionally, long-term operation electroluminescence measurements (up to 5000 hours) indicate that the LMA approach affects the nano-LEDs performance as well as device lifetime and reliability advantageously. The results presented demonstrate the suitability and reliability of the vertically integrated nano-LEDs conditioned locally/selectively by LMA as a key component for future on chip integrated electro-optic convertors. They could play an important role in the development of novel optical computing architectures based on transmistor/all optical switch units. Figure 1: Scanning electron micrograph of a single nano-LED structure with its nickel cap (serving as the etching mask) after the RIE process. The “base” region of the nano-LED exhibits a “shallower” chemical/physical corrosion depth. Figure 2: micro electroluminescence map-ping, after the “conditioning” procedure, performed on nano-LEDs in an array with different annealing conditions: non-locally annealed E0 and locally E1 and E2 annealed

Residual strain in recessed AlGaN/GaN heterostructure field-effect transistors evaluated by micro photoluminescence measurements

The residual strain in AlGaN/GaN heterostructure field-effect transistors (HFETs) with recessed gates and their non-recessed counterparts were investigated by micro photoluminescence measurements (μ-PL). It is found that strain relaxation accounts for the observed sheet carrier density reduction after gate recessing. The usefulness of the method for device processing optimization is demonstrated. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim