• Nuclear Engineering and Technology
• /
• v.55 no.11
• /
• pp.4238-4245
• /
• 2023

In order to predict the lifetime of InP Heterojunction Bipolar Transistor (HBT) devices and related circuits in the space radiation environment, a novel model including gamma radiation effects is proposed in this paper. Based on the analysis of radiation-induced device degradation effects including both DC and AC characteristics, a set of empirical expressions describing the device degradation trend are presented and incorporated into the Keysight model. To validate the effective of the proposed model, a series of radiation experiments are performed. The correctness of the novel model is validated by comparing experimental and simulated results before and after radiation.

• Journal of Radiation Protection and Research
• /
• v.48 no.3
• /
• pp.124-130
• /
• 2023

Background: When bipolar junction transistors (BJTs) are used as switches, their switching characteristics can be deteriorated because the recombination time of the minority carriers is long during turn-off transient. When BJTs operate as low frequency switches, the power dissipation in the on-state is large. However, when BJTs operate as high frequency switches, the power dissipation during switching transients increases rapidly. Materials and Methods: When silicon (Si) BJTs are irradiated by fast neutrons, defects occur in the Si bulk, shortening the lifetime of the minority carriers. Fast neutron irradiation mainly creates displacement damage in the Si bulk rather than a total ionization dose effect. Defects caused by fast neutron irradiation shorten the lifetime of minority carriers of BJTs. Furthermore, these defects change the switching characteristics of BJTs. Results and Discussion: In this study, experimental results on the switching characteristics of a pnp Si BJT before and after fast neutron irradiation are presented. The results show that the switching characteristics are improved by fast neutron irradiation, but power dissipation in the on-state is large when the fast neutrons are irradiated excessively. Conclusion: The switching characteristics of a pnp Si BJT were improved by fast neutron irradiation.

• Journal of Electrical Engineering and Technology
• /
• v.6 no.4
• /
• pp.535-538
• /
• 2011

The electromodulation methods of photoreflectanceand the related technique of contactless electroreflectance(CER) are valuable tools in the evaluation of important device parameters for structures such as heterojunction bipolar transistors, pseudomorphic high electron mobility transistors, and quantum dots(QDs). CER is a very general principle of experimental physics. Instead of measuring the optical reflectance of the material, the derivative with respect to a modulating electric field is evaluated. This procedure generates sharp, differential-like spectra in the region of interband (intersubband) transitions. We conduct electric-optical studies of both GaAs layers and InAs selfassembled QDs grown by molecular beam epitaxy. Strong GaAsbandgap energy is measured in both structures. In the case of lnAs monolayers in GaAs matrices, the strong GaAsbandgap energy is caused by the lateral quantum confinement.

• Journal of information and communication convergence engineering
• /
• v.7 no.2
• /
• pp.215-218
• /
• 2009

In this paper, temperature stable current and voltage references using simple CMOS bias circuit are proposed. To obtain temperature stable characteristics of bias circuit a bandgap reference concept is used in a conventional circuit. The parasitic bipolar transistors or MOS transistors having different threshold voltage are required in a bandgap reference. Thereby the chip area increase or the extra CMOS process is required compared to a standard CMOS process. The proposed reference circuit can be integrated on a single chip by a standard CMOS process without the extra CMOS process. From the simulation results, the reference current variation is less than ${\pm}$0.44% over a temperature range from - $20^{\circ}C$ to $80^{\circ}C$. And the voltage variation is from - 0.02% to 0.1%.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.3
• /
• pp.784-794
• /
• 1996

In this papre, the design and the fabrication of the surface mountable voltage controlled oscillator is described for local oscillator in PCS(WACS/TDMA) handset. The VCO employs two silicon bipolar transistors of $f_{gamma}$ of 4 GHz as active devices. These are asembled to form the VCO on the 4 layer PCB of the size $12{\times}10mm$which provides the strip line resonator at the third layer. The fabricated VCO shows tuning rage over 50 MHz, phase noise -100 dBc/Hz at the 100 kHz frequency offset, and 0 dBm output power with the consumption of 22 mA at 3V. It is belived that the size will be more reduced by employing 1005 chip components and that the current consumption will be improved by employing transistors of higher $f_{gamma}$.

• Journal of the Korean Vacuum Society
• /
• v.14 no.4
• /
• pp.229-237
• /
• 2005

The degradation phenomena in SiGe hetero-junction bipolar transistors(SiGe HBTs) induced by bias stress are investigated in this review. If SiGe HBTs are stressed over a specific time interval, the device parameters deviate from their nominal values due to the internal changes in the devices. Reverse-bias stress on emitter-base(EB) junctions causes base current increase and current gain decrease because carriers accelerated by the electrical field generate recombination centers. When forward-bias current stress is conducted at an ambient temperature above $140^{\circ}C$ , hot carriers produced by Auger recombination or avalanche multiplication induce current gain fluctuation. Mixed-mode stressing, where high emitter current and high collector-base voltage are simultaneously applied to the device, provokes base current rise as EB reverse-bias stressing does.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.5
• /
• pp.1805-1811
• /
• 2017

Recently, DC systems are considered as efficient electric power systems for renewable energy based clean power generators. This discloses several critical issues that are required to be considered before the installation of the DC systems. First of all, voltage/current switching stress, which is aggravated by large fault current, might damage DC circuit breakers. This problem can be simply solved by applying a superconducting fault current limiter (SFCL) as proposed in this study. It allows a simple use of insulated-gate bipolar transistors (IGBTs) as a DC circuit breaker. To evaluate the proposed resistive type SFCL application to the DC circuit breaker, a DC distribution system is composed of the practical line impedances from the real distribution system in Do-gok area, Korea. Also, to reflect the distributed generation (DG) effects, several DC-to-DC converters are applied. The locations and sizes of the DGs are optimally selected according to the results of previous studies on DG optimization. The performance of the resistive type SFCL applied DC circuit breaker is verified by a time-domain simulation based case study using the power systems computer aided design/electromagnetic transients including DC (PSCAD/ EMTDC(R)).

• Journal of the Korea Society for Simulation
• /
• v.4 no.2
• /
• pp.41-60
• /
• 1995

The IGBT(Insulated Gate Bipolar Transistor) is a power semiconductor device that has gained acceptance among circuit design engineers for motor drive and power converter applications. IGBT devices(International Rectifier, Proposed proposed model etc) have the best features of both power MOSFETs and power bipolar transistors, i.e., efficient voltage gate drive requirememts and high current density capability. When designing circuit and systems that utilize IGBTs or other power semiconductor devices, circuit simulations are needed to examine how the devices affect the behavior of the circuit. The interaction of the IGBT with the load circuit can be described using the device model and the state equation of the load circuit. The voltage rise rate at turn-off for inductive loads varies significantly for IGBTs with different base life times, and this rate of rise is important in determing the voltage overshoot for a given series resistor-inductor load circuit. Excessive voltage overshoot is potentially destructive, so a snubber protection circuit may be required. The protection circuit requirements are unique for the IGBT and can be examined using the model. The IGBT model in this paper is verified by comparing the results of the model with experimented results for various circuit operating conditions. The model performs well and describes experimented results accurately for the range of static and dynamic condition in which the device is intended to be operated.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.19 no.3
• /
• pp.93-98
• /
• 2005

Silicon bipolar transistors (Si-BJT) are widely used in the telecommunication system such as short range wireless control and wireless indoor voice communication system. New modeling method for the internal current source model of Si-BJT is proposed. The proposed method based on new thermal resistance extraction method and new analytical expressions for the current source parameters of Si-BJT. The proposed method can directly extract the model parameters without any optimization procedure which is adopted in the conventional modeling method. The proposed method is applied to 5 finger $0.4\times20[{\mu}m^2]$ and the model shows good prediction of the measured data in $3[\%]$ of errors proving the validity of this method.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.385-385
• /
• 2012

A two terminal N+/P/N+ junction device to replace the conventional selective transistor was studied as a bilateral switching device for spin transfer torque (STT) MRAM based on 3D device simulation. An N+/P/N+ junction structure with $30{\times}30nm$ area requires bi-directional current flow enough to write a data by a drain induced barrier lowering (DIBL) under a reverse bias at N+/P (or P/N+ junction), and high current on/off ratio of 106. The SiGe materials are widely used in hetero-junction bipolar transistors, bipolar compensation metal-oxide semiconductors (BiCMOS) since the band gap of SiGe materials can be controlled by changing the fraction and the strain epilayers, and the drift mobility is increased with the increasing Ge content. In this work, N+/P/N+ SiGe material based junction provides that drive current is increased from 40 to $130{\mu}A$ by increased Ge content from 10~80%. When Ge content is about 20%, the drive current density of SiGe device substantially increased to 2~3 times better than Si-based junction device in case of 28 nm P length, which is sufficient current to operation of STT-MRAM.