Forward Current Gain Research Articles

An arduino experiment for measuring the base amplification factor of NPN transistors

The hFE of a transistor, or commonly known as the hybrid parameter forward current gain, is one of the important factors that characterizes the working of a transistor in any circuit. So designing such an experiment with readily available materials would help STEM students gain more intuition about the working principle of transistors in general. In this experiment we had used an Arduino UNO microcontroller along with some resistors and by using Ohm’s law we were able to deduce a formula for the hFE (hybrid parameter current gain) of any npn transistor used in the circuit, just by measuring the voltages across the input and output resistors used along with the transistor in a common emitter configuration.

Nonalloyed Ohmic Contacts in AlGaN/GaN HEMTs With MOCVD Regrowth of InGaN for Ka-Band Applications

Low-resistance ohmic contacts in AlGaN/GaN high-electron-mobility transistor (HEMT) devices require high-temperature (HT) annealing (>800 °C) which can deteriorate material quality, surface morphology, and edge acuity of the metal stacks. This article demonstrates the highfrequency and high-power performance of the AlGaN/GaN HEMT devices with low-temperature metal-organic chemical vapor deposition (MOCVD) regrown degenerately doped InGaN ohmic contacts compared with GaN-based regrown contacts. Ohmic contacts fabricated by regrowth methods could be a valuable alternative for both metal-based alloyed ohmic contacts and implantation-based ohmic contacts. Using a T-gate and MOCVD regrown InGaN ohmic contacts, the AlGaN/GaN HEMT with an Lg of 150 nm and S-D spacing of 2.5 μm demonstrated a maximum drain current of 0.94 A/mm and a peak transconductance of 337 mS/mm. The same device exhibited a forward current gain frequency ft of 36.8 GHz and a maximum frequency of oscillation fmax of 75.0 GHz. A power density of 3.07 W/mm with a 60% drain efficiency was measured at 35 GHz with a Vds of 20 V and a quiescent current of 100 mA/mm.

Characterizing and modeling current gain degradation in bipolar transistor exposed to heavy ion radiation

Radiation effects of 20 MeV Br on bipolar transistors are investigated in this work. A distinct different bias dependences are found for damage factors (DF) of forward and reverse current gain. For reverse current gain, DF gradually decreases with the voltage across base-collector junction (VBC) increasing, until a saturated value is reached. While an unexpected increase exists in DF of forward current gain over the high voltage across base-collector junction (VBE) region. The high injection effect is found to contribute to the observed rebound for forward current gain over high VBE region. From the device physical perspective, a physics-based analytical closed DF model for forward and reverse current gain is proposed, including the contribution of high injection effect and recombination current in junction space charge region. A good agreement is obtained between the measured and modeled data over the whole bias region.

Effects of traps in the gate stack on the small-signal RF response of III-V nanowire MOSFETs

We present a detailed study of the effect of gate-oxide-related defects (traps) on the small-signal radio frequency (RF) response of III-V nanowire MOSFETs and find that the effects are clearly identifiable in the measured admittance parameters and in important design parameters such as h21 (forward current gain) and MSG (maximum stable gain). We include the identified effects in a small-signal model alongside results from previous investigations of III-V RF MOSFETs and thus provide a comprehensive physical small-signal RF model for this type of transistor, which accurately describes the measured admittance parameters and gains. We verify the physical basis of the model assumptions by calculating the oxide defect density from the measured admittances.

Black Phosphorus High-Frequency Transistors with Local Contact Bias.

Having a sizable band gap and high carrier mobility, black phosphorus (BP) is a promising two-dimensional material for high-frequency electronic and optoelectronic devices. Further, for metal-oxide-semiconductor field-effect transistors (MOSFETs) operating at high frequencies, they must have a top gate of submicron length instead of the commonly used global back gate. However, without the global back gate to electrostatically induce doping in BP, top-gated submicron BP MOSFETs have not reached their full potential mainly due to large contact resistances. Here, we report top-gated submicron BP MOSFETs with local contact bias electrodes to induce doping in the contact region. This resulted in reduced contact resistance and, in turn, orders of magnitude improvement in current capacity (>500 μA/μm) and peak transconductance (>40 μS/μm), if compared with top-gated BP transistors without any back-gating scheme. In turn, these improvements resulted in a forward current gain cutoff frequency of 37 GHz and a maximum frequency of oscillation of 22 GHz at room temperature, the highest reported for BP MOSFETs up to date.

An LTspice Simulation Model of Gamma-radiation Effects and Annealing in a Voltage Regulator With a Lateral Serial PNP Transistor With Round Emitters

The aim of this paper was to determine the reasons for a complex radiation response of the commercial-off-the-shelf LM2940CT5 low-dropout voltage regulator. Examination of this circuit in a gamma-radiation environment disqualified its use when operated with relatively high output currents, while its radiation tolerance was satisfactory when load current was approximately one-tenth (or lower) of the nominal value. In order to obtain a more thorough insight into the radiation response of this integrated circuit, a detailed SPICE model was developed. This model enabled mutual comparison of the influence of serial and driver PNP power transistor parameters: forward emitter current gain, knee current and emitter resistance. The serial lateral PNP power transistor with round emitters was identified as the weakest element that crucially affected the entire circuit radiation tolerance. The effects of gamma-radiation were examined for total doses up to 500 Gy followed by three sequences of isothermal annealing. Detailed characteristics of Beta(Ic) were procured for four different kinds of bias and load conditions during irradiation. The emitter resistance increase of the serial power transistor was a primary reason for the low radiation tolerance of the entire voltage regulator; it was much more influential than the perceived decline of the PNP power transistor forward emitter current gain. The influence of bias and load conditions were analysed with buildup of interface traps and the oxide-trapped charge, which affected the radiation and post-irradiation response of the serial power transistor.

High Temperature High Current Gain IC Compatible 4H-SiC Phototransistor

This paper presents our in-house fabricated 4H-SiC n-p-n phototransistors. The wafer mapping of the phototransistor on two wafers shows a mean maximum forward current gain (βFmax) of 100 at 25 °C. The phototransistor with the highest βFmax of 113 has been characterized from room temperature to 500 °C. βFmax drops to 51 at 400 °C and remains the same at 500 °C. The photocurrent gain of the phototransistor is 3.9 at 25 °C and increases to 14 at 500 °C under the 365 nm UV light with the optical power of 0.31 mW. The processing of the phototransistor is same to our 4H-SiC-based bipolar integrated circuits, so it is a promising candidate for 4H-SiC opto-electronics on-chip integration.

Computer Simulation Model for Evaluation of Radiation and Post-Irradiation Effects in Voltage Regulator with Vertical PNP Power Transistor

The aim of the presented research was to develop a faithful SPICE simulation model of radiation and post-irradiation effects in a low-dropout voltage regulator with a vertical serial PNP transistor. The main parameters for the analysis of the circuit’s radiation response were the voltage regulator’s maximum output current and the minimum dropout voltage, as well as the serial transistor’s excess base current. All the data, comprised of the old irradiation and new annealing results, were unified and normalised, in order to enable a broad insight in the radiation tolerance of the examined circuits. Initial radiation effects, as well as the late post-irradiation effects, were successfully simulated using the variations of the maximum forward emitter current gain and knee current of the serial PNP power transistor. Ten-year room temperature annealing led to a significant recovery of the serial transistor’s excess base current, yet the maximum output current and minimum dropout voltage, in most cases, expressed further degradation. On the other hand, two short-term, high-temperature annealing periods led to the tremendous recovery of all of the irradiated voltage regulators, reducing the circuit degradation down to the level perceived after absorption of nearly 10% of the total ionising dose.

Analysis of Hybrid Parameters of a Single Stage Small Signal Transistor Amplifier Using Two-Port Network

This paper presents the analysis of the h-parameter of a single stage small signal transistor amplifier using two-port network. This is motivated by the need to have the rudimentary knowledge of the h-parameter transistor analysis model and to demonstrate its equivalence in the three configuration of the transistor. In this analysis, it was borne in mind the characteristics of a small signal operating conditions of the transistor. Among these characteristics is the assumption that Small – signal operations applies when variations are restricted to such a small amplitude that the partial differential derivatives can be applied. In the methodology, the transistor two-port network was used in deriving the hybrid parameter performance quantities from the first principle by applying partial derivative mathematical tool. The four variables of the input and output of the two-port network namely the currents and voltages which could be combined in six different ways were identified. These were described and analyzed by mathematical functions which relates one of the four variables to two other variables at a time, and by this, six various functions were generated. The partial derivatives of these functions were obtained and these gave the performance quantities which are the key components of the h parameter equations. The initial conditions of each of the component parameters where properly observed and substituted appropriately. This was then transformed into the equivalent circuits of the three transistor configurations. Since the transistor is frequently used for the amplification of sinusoidal currents, the changes in instantaneous total voltage and current were then replaced by root mean square ac quantities, which are considered to be impressed on the direct value. The results obtained are the basic h-parameter equations and the key components of the h parameter transistor model namely the Input Resistance, the Reverse Voltage Gain, the Forward Current Gain and the Output Admittance.

Analisis Kecepatan Switching IC TTL AOI Terhadap Nilai Optimal Karakteristik Bf

This study analyzes the speed of propagation time performance capabilities of the integrated circuit type of standard Dual 3-Wide 3-Input TTL IC AOI on the characteristic levels of forward common emitter current gain (βf). Simulation is carried out using SPICE software with capacitor load (CL) of 15 pf and levels of forward common emitter current gain (βf) are 5, 10, and 15. The simulation results show that tPLH (transition low to high), tPHL (transitions high to low), and mean time propagation produced differ for each βf. A propagation time of 1.59ns is obtained for βf of 5, slower than βf performance of 10, which is 1.53ns. Furthermore, βf performance with a value of 15 is 1.50ns, faster than others’. But this βf has greater power dissipation, which is 29 mW. Power dissipation produced by βf of 10 is 27 mW, and βf of 5 produced 26 mW. Therefore, IC designing must consider the characteristic level of the forward common emitter current gain (βf) value. Higher βf values produce larger power dissipation.

Curvature-correction in the bandgap voltage reference based on thermal compensation of beta and base-emitter voltage

A novel current-mode bandgap voltage reference circuit is presented. The proposed architecture exhibits the curvature compensation ability. The curvature compensation is achieved by utilising the nonlinear behaviour of forward current gain (β) to compensate nonlinear temperature dependence of base-emitter voltage (VBE). The proposed voltage reference is analysed theoretically and compared with other existing methods. The circuit is designed and simulated in standard 180 nm mixed mode CMOS technology which gives a bandgap reference level of 1.243 V. The minimum required supply voltage is 1.5 V. The maximum current drawn from VDD is 3.8 µA. A temperature coefficient of 4.5 ppm/°C is achieved over −25°C to 125°C temperature range. Variation in reference voltage is ± 15 mV across process corners. The reference circuit exhibits −65 dB low-frequency PSNA at 10 Hz with line sensitivity of 5 mV/V.

Egg incubator control system with short message service (sms) fault analysis alert

The egg incubator system with temperature sensor can measure the state of the incubator and automatically change to the suitable condition for the egg. The health of the egg is very important for the development of embryo. The status condition in the incubator system will appear on the liquid crystal display (LCD) screen. To make sure all part of egg was heated by lamp, direct current (DC) motor was used to rotate iron rod at the bottom side and automatically change the position of egg. The entire element is controlled using programmable integrated circuit (PIC) – a type of microcontroller that can process a data from sensor and will execute the control element to change the condition of the incubator system. The heater is interfaced with the controller through the optocoupler. The optocoupler isolates the microcontroller from the alternating current (AC) power, thereby preventing any possible flow back of the AC into the control circuit. The software intelligent agent was embedded into 8051 family of micro controllers, emulating the attention commands of mobile cell phone using window HyperTerminal and microcontroller and thus translate attention commands to assembly language, having machine cycle of 1.085s,R=10K,C=10iF, t=2.17is,transistor collector current, Ic=800mA and emitter forward current gain, hfe gives 200.The SMS mobile cell phone using AT89C51 microcontroller in the prototype self diagnostic systems, will not only control the temperature of an incubator but also detect and analyze faults in the system. The programme used in this work is user friendly since the incubator system can move to other places. Keywords : Microcontroller, Optocoupler, Programmable Integrated Circuit (PIC) and Window HyperTerminal

Degradation differences in the forward and reverse current gain of 25 MeV Si ion irradiated SiGe HBT

The silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs) were exposed to 25MeV Si ions with ion fluence from 9.1×108 to 4.46×1010ions/cm2 at room temperature. The forward current gain (βF) and reverse current gain (βR) were studied before and after irradiation and the bias dependences of the displacement damage factor for βF and βR were also presented. Measurement results indicated that βF and βR all decline with the ion fluence increasing. The reciprocal of βR was found to vary linearly throughout all ion fluence for arbitrary base-collector voltage. However, a non-linear behavior for the reciprocal of βF appeared at low fluence for the low and medium base-emitter voltage. Besides, it was found that the bias dependence of displacement damage factor for βF was significantly different from that for βR. The underlying physical mechanisms were analyzed and investigated in detail.

Power lateral pnp transistor operating with high current density in irradiated voltage regulator

The operation of power lateral pnp transistors in gamma radiation field was examined by detection of the minimum dropout voltage on heavily loaded low-dropout voltage regulators LM2940CT5, clearly demonstrating their low radiation hardness, with unacceptably low values of output voltage and collector-emitter voltage volatility. In conjunction with previous results on base current and forward emitter current gain of serial transistors, it was possible to determine the positive influence of high load current on a slight improvement of voltage regulator LM2940CT5 radiation hardness. The high-current flow through the wide emitter aluminum contact of the serial transistor above the isolation oxide caused intensive annealing of the positive oxide-trapped charge, leading to decrease of the lateral pnp transistor's current gain, but also a more intensive recovery of the small-signal npn transistors in the control circuit. The high current density in the base area of the lateral pnp transistor immediately below the isolation oxide decreased the concentration of negative interface traps. Consequently, the positive influence of the reduced concentration of the oxide-trapped charge on the negative feedback reaction circuit, together with the favourable effect of reduced interface traps concentration, exceeded negative influence of the annealed oxide-trapped charge on the serial pnp transistor's forward emitter current gain.

Simultaneous and Sequential Radiation Effects on NPN Transistors Induced by Protons and Electrons

This paper examines individual radiation effects caused by 110 keV electrons and 170 keV protons, and combined radiation effects induced by 110 keV electrons together with 170 keV protons on the forward current gain of NPN bipolar junction transistors (3DG130, 3DG112). Key parameters were measured in-situ and the change in current gain of the NPN bipolar junction transistors is obtained at a fixed voltage of base-emitter junction (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BE</sub> ) during simultaneous and sequential exposures. Experimental results show that the current gain degradation of the NPN bipolar junction transistors is sensitive to both of ionization and displacement damage. The ionization damage is primarily caused by 110 keV electrons, while the displacement damage is mainly induced by 170 keV protons in this investigation. Based on the simultaneous and sequential exposure results, the ionization damage caused by 110 keV electrons can give an enhancing effect to displacement damage induced by 170 keV protons for NPN bipolar junction transistors.

Synergistic Radiation Effects on PNP Transistors Caused by Protons and Electrons

This paper examines individual radiation effects caused by 110 KeV electrons, 70 KeV electrons and 170 KeV protons, and combined radiation effects induced by 110 KeV electrons together with 170 KeV protons and 70 KeV electrons with 170 KeV protons on the forward current gain of bipolar junction transistors (3CG130, PNP). The combined radiation effects include simultaneous and sequential radiation effects. Key parameters were measured in-situ and the change in current gain of the PNP transistors is obtained at a fixed voltage of emitter-base junction . Experimental results show that the current gain degradation of the PNP transistors is sensitive to both of ionization and displacement damage. The ionization damage is primarily caused by 110 KeV and 70 KeV electrons, while the displacement damage is mainly induced by 170 KeV protons in this investigation. Based on the simultaneous and sequential exposure results, the ionization damage caused by 110 KeV and 70 KeV electrons could give annealing-like and enhancing effects to displacement damage induced by 170 KeV protons for PNP BJTs.

Minimum dropout voltage on a serial pnp transistor of a moderately loaded voltage regulator in a gamma radiation field

The main examined value in an experiment performed on moderately loaded voltage regulators was the serial pnp transistor?s minimum dropout voltage, followed by the data on the base current and forward emitter current gain. Minimum dropout voltage decreased by up to 12%, while the measured values of the forward emitter current gain decreased by 20-40% after the absorption of a total ionizing dose of 500 Gy. The oxide trapped charge increased the radiation tolerance of the serial lateral pnp transistor owing to the suppression of interface trap formation above the base area. Current flow through the serial transistor of the voltage regulator had an influence on the decrease in the power pnp transistor?s forward emitter current gain. Due to the operation with a moderate load of 100 mA, loss of emitter injection efficiency was not as important as during the operation with high current density, thus eliminating the negative influence of emitter crowding on the radiation hardness of the voltage regulator. For a moderate load, gain in the negative feedback reaction was enough to keep output voltage in the anticipated range. Only information procured from tests of the minimum dropout voltage on the moderately loaded voltage regulators were not sufficient for unequivocal determination of the examined integrated circuit?s radiation hardness.

On-line monitoring of base current and forward emitter current gain of the voltage regulator's serial pnp transistor in a radiation environment

A method of on-line monitoring of the low-dropout voltage regulator's operation in a radiation environment is developed in this paper. The method had to enable detection of the circuit's degradation during exploitation, without terminating its operation in an ionizing radiation field. Moreover, it had to enable automatic measurement and data collection, as well as the detection of any considerable degradation, well before the monitored voltage regulator's malfunction. The principal parameters of the voltage regulator's operation that were monitored were the serial pnp transistor's base current and the forward emitter current gain. These parameters were procured indirectly, from the data on the voltage regulator's load and quiescent currents. Since the internal consumption current in moderately and heavily loaded devices was used, the quiescent current of a negligibly loaded voltage regulator of the same type served as a reference. Results acquired by on-line monitoring demonstrated marked agreement with the results acquired from examinations of the voltage regulator's maximum output current and minimum dropout voltage in a radiation environment. The results were particularly consistent in tests with heavily loaded devices. Results obtained for moderately loaded voltage regulators and the risks accompanying the application of the presented method, were also analyzed.

60Co γ-ray induced gain degradation in bipolar junction transistors

Commercial indigenously made npn and pnp bipolar junction switching transistors used for space applications are investigated for 60Co γ-ray induced effects. The on-line as well as off-line measurements indicate that the forward current gain of the transistors decreases significantly as the accumulated dose increases. Excess base current model is employed to account for the current gain degradation. The pnp transistor undergoes as much degradation as the npn type. It is found that bulk degradation by displacement damage is the dominant mechanism leading to reduction in forward current gain of npn transistors. On the other hand it appears that, in addition to bulk damage, surface degradation due to accumulation of interface states at the silicon-silicon dioxide interface also contributes significantly to gain degradation in pnp transistor as evident from thermal annealing studies. Further, estimation reveals that the transistor with larger base width has higher displacement damage factor.

Combined Radiation Effects of Protons and Electrons on NPN Transistors

This paper examines individual radiation effects caused by 110 keV electrons, 70 keV protons and 170 keV protons, and combined radiation effects induced by 110 keV electrons together with 70 keV protons and 110 keV electrons with 170 keV protons on the forward current gain of bipolar junction transistors (3DG112D, NPN). Key parameters were measured in-situ and the change in current gain of the NPN transistors is obtained at a fixed collector current. Experimental results show that the current gain degradation of the NPN transistors is sensitive to both of ionization and displacement damage. The ionization damage is primarily caused by 110 keV electrons, while the displacement damage is mainly induced by 170 keV protons in this study. Under the combined exposure of 170 keV protons and 110 keV electrons, the current gain degradation lies between those given by the individual irradiations. The current gain degradation is mainly caused by the 170 keV protons, and the 110 keV electrons mitigate the degradation to some extent. In the case of combined irradiation of 110 keV electrons and 70 keV protons, no synergistic effect occurs, the current gain degradation is basically controlled by the 110 keV electrons.