Resonant Tunneling Bipolar Transistor Research Articles

Ultra-sensitive current bistability and light switching in a resonant tunneling superlattice transistor

Bistability in the current–voltage characteristics of semiconductor superlattices and quantum cascade laser structures has the potential for wide-ranging applications, particularly in sensing systems. However, the interdependency of applied bias and current injection in conventional two-terminal structures has led to complications in analysis and rendered the bistability phenomenon difficult to implement in practical applications. Here, we report a new kind of electronic bistability coupled to optical switching in a resonant tunneling bipolar superlattice transistor. This bistability manifests as sharp discontinuities in the collector current with extremely small variations of the applied voltage, which arise from unstable tunneling transmission across the hetero-barrier between the two-dimensional electron gas (2DEG) at the edge of the transistor base and the collector superlattice structure. The electronic transitions between high and low quantum mechanical transmissions are demonstrated to be caused by self-consistent variations of the internal electric field at the heterointerface between the 2DEG and the superlattice. They are also present in the base current of the three-terminal device and result in sharp switching of near-infrared spontaneous light emission output from an interband radiative recombination process with a peak emission wavelength of 1.58 μm. A comprehensive quantum mechanical theoretical model accounting for the self-consistent bistable tunneling transmission is in quantitative agreement with the experimental data. The measured peak transconductance sensitivity value of 6000 mS can be used in the highly sensitive detector and non-linear device applications.

Multiple negative differential resistance of InP/InGaAs superlattice-emitter resonant-tunneling bipolar transistor at room temperature

Sequential resonant-tunneling behavior of a resonant-tunneling bipolar transistor with five-period i-InP/n-InGaAs superlattice emitter has been demonstrated. An interesting multiple negative differential resistance (NDR) phenomena resulting from the creation and extension of the high-field domain in a superlattice is observed at room temperature. Furthermore, the employing of a thin n-InGaAs emitter layer between an InP/InGaAs superlattice and p+-InGaAs base layer helps to lower the potential spike at the base–emitter junction and the reduce neutral–emitter recombination current. Experimentally, transistor performance, incorporating multiple NDR, with a relatively large current gain of 454 and an offset voltage as low as 80 mV, is achieved.

Investigation of InP/InGaAs superlattice-emitter resonant tunneling bipolar transistor at room temperature

In this paper, a new InP/InGaAs superlattice-emitter resonant tunneling bipolar transistor (SE-RTBT) has been successfully fabricated and demonstrated. The employing of a thin n-InGaAs emitter between InP/InGaAs superlattice and p +-InGaAs base helps to lower potential spike and reduce neutral-emitter recombination current, simultaneously. Furthermore, InP/InGaAs superlattice resulted from tunneling injection can reduce the spread of thermal distribution and non-radiative recombination cross-section. Experimentally, the studied device exhibits a common-emitter current gain as high as 670 and low collector–emitter offset voltage of 60 mV at room temperature. To our knowledge, the device exhibits the largest current gain when compared to the previously reported SE-RTBTs.

High-sensitivity x-ray photoelectron spectroscopy characterization of a quantum device structure

A high-resolution, high-sensitivity VG x-ray photoelectron spectrometer was used to study a semiconductor layer structure grown for the fabrication of resonant tunneling bipolar transistor devices. Depth profiling using argon ion milling, at a rate of 50 Å/min, has allowed the device layers to be identified on the basis of their elemental composition. The measurement system sensitivity was sufficient to identify the elemental components of the 11 Å AlAs barrier layer in quantum tunneling InGaAs/AlAs device layers.

Investigation of InP/InGaAs superlattice-emitter resonant tunneling bipolar transistors (RTBTs)

An InP/InGaAs superlattice-emitter resonant tunneling bipolar transistor (SE-RTBT) has been fabricated and demonstrated. The influence of the superlattice and emitter thickness on the device characteristics is studied. The insertion of the superlattice and a well-designed emitter improve the characteristics of the SE-RTBT. Common-emitter current gains up to 170 and 54 are obtained for the studied devices with emitter thicknesses of 800 Å and 150 Å, respectively. Based on the specified structure, the lower offset voltage and saturation voltage ( ≤1.5 V) are obtained. Experimentally, the device with a 5-period superlattice and an emitter thickness of 800 Å provides higher dc performance and stable temperature-dependent characteristics.

Investigation of an AlInAs/GaInAs superlattice-emitter resonant tunneling bipolar transistor (SE-RTBT)

A new bipolar transistor with a 20-period i-AlInAs/n+-InGaAs superlattice, prepared by metal organic chemical vapour deposition, has been fabricated and demonstrated. This superlattice is used as a confinement barrier for holes and a resonant tunneling (RT) route for electrons. Due to the RT effect within the 20-period superlattice near emitter–base p–n junction region, the N-shaped negative-differential-resistance (NDR) phenomena are observed under normal operation. A transistor action with a common-emitter current gain of 13 and a small offset voltage (∼90 mV) is achieved at room temperature.

InGaP/GaAs superlattice-emitter resonant tunneling bipolar transistor (SE-RTBT)

In this letter, a new InGaP/GaAs superlattice-emitter resonant tunneling bipolar transistor (SE-RTBT) is fabricated and demonstrated. A 5-period InGaP/GaAs superlattice is used to serve the RT route and the confinement barrier for minority carriers. Due to the large valence band discontinuity (/spl Delta/E/sub v/) at the InGaP/GaAs heterointerface, a high current gain (/spl beta//sub max//spl sime/220) is obtained. Furthermore, the interesting N-shaped negative-differential-resistance (NDR) phenomena resulting from RT effect are found both in the saturation and forward-active region of current-voltage (I-V) characteristics at room temperature.

Multi-state superlattice-emitter resonant-tunneling bipolar transistor with circuit applications

A superlattice-emitter resonant-tunneling bipolar transistor (SE-RTBT) has been successfully fabricated using GaAs based materials and demonstrated in this paper. In an SE-RTBT, the i-Al0·5Ga0·5As/n+-GaAs superlattice is used as a reflection and resonant tunneling barrier. High emitter injection efficiency and hence high current gain are sustained. In the transistor operation, a current gain of 65 was obtained with double-negative differential resistance. The experimental processes and device D.C. performance were demonstrated first. Then a great number of circuit applications, i.e. frequency multiplier, multiple-valued logic, and parity bit generator, using the SE-RTBT and exhibiting reduced complexities will be discussed. Thus, the SE-RTBT offers strong potential for use in very high-speed and high density integrated circuits.

Effects of base-emitter junction on the resonant tunneling bipolar transistor with double barriers in teh emitter

A resonant-tunneling bipolar transistor with a series of double barriers (DBs) in the emitter grown by molecular beam epitaxy was studied. The current-voltage characteristics exhibiting S-shaped negative differential resistance (NDR) but not N-shaped NDR behavior were observed. Due to the influence of the base-emitter junction which cannot reach a flatband condition at the resonant situation, the subband level of the DB is smaller than the electrostatic potential of the base-emitter (B-E) junction. Thus the N-type NDR cannot be observed. With further increasing bias, avalanche breakdown occurs in the base-collector (B-C) junction to produce electron-hole pairs. Multiple S-shaped NDR behavior is observed in the collector current-voltage ( I C- V CE) characteristics from holes sequentially accumulated at the valence band maxima of teh base region and a series of DB heterostructures in the emitter. Transistor behavior is observed for high-level base injection (e.g. 1 mA/step) while the switching characteristics of a thyristor are observed for low-level base injection (e.g. 50 μA/step). The multistate operation of the new phenomenon opens up opportunities for digital and analog circuits with greatly reduced complexity and multiple valued logic.

A new resonant-tunneling bipolar transistor with triple-well emitter structure

A new resonant-tunneling bipolar transistor with triple-well emitter structure

A new functional, resonant-tunneling bipolar transistor with a superlattice emitter

We report a new resonant-tunneling bipolar transistor (RBT), in which electrons are injected from emitter to base by resonant-tunneling through the minibands in the i-AlGaAs/n+-GaAs superlattice emitter. The main feature of the device is the significant double negative-differential-resistance both at room temperature and low temperature. Two high peak-to-valley (PV) current ratios of 4:1 and 2.6:1 were obtained at 77 K. In the common emitter configuration, bistable output currents exist as controlled by the base-emitter voltage at critical values of VBE = 2.5 V and VBE = 3 V, respectively. In addition, two negative transconductance operation regions were obtained when the base-emitter voltage was applied. Yet, three different transistor action regions occur as the control base current is being applied. For base currents that are not high enough to bring the base-emitter junction to flat-band condition, common-emitter current gain up to 65 was obtained. This is the highest value ever reported in an RBT device using GaAs based materials. As control base current increases sufficiently to cause the base-emitter voltage drop beyond the flat-band condition, two different transistor action regions with smaller current gains of 38 and 35 are found. Furthermore, the first peak current is nearly equal to the second peak current and much larger than the second valley current. Thus the proposed device is attractive for multiple-valued logic circuits and frequency multipliers.

The Use of Tertiarybutylphosphine and Tertiarybutylarsine for the Metalorganic Molecular Beam Epitaxial Growth of Resonant Tunneung Devices

ABSTRACTWe report on the use of thermally-cracked tertiarybutylphosphine (TBP) and tertiarybutylarsine (TBA) with elemental Ga, In, and Al sources for the MOMBE growth of InP-based resonant tunneling diode (RTD) and resonant tunneling bipolar transistor (RTBT) structures. We have systematically examined the effects of growth conditions and heterostructure modifications on the InP/lnGaAs RTD including the use of pseudomorphic (InGa)P barriers and, in addition, explored for the first time, InP quantum well RTDs using both AlAs and InGaP barriers. Cross-sectional transmission electron microscopy has been used to correlate the structural quality with the electrical characteristics for both lattice-matched and pseudomorphic layers composed of InAs, AlAs, and InGaP. We also demonstrate the first use of mixed InP/lnGaAs and AlAs/lnGaAs heterojunctions in the RTBT. These transistors exhibit room temperature negative transconductance and a peak-to-valley current ratio of 35, the highest yet observed In the RTBT.

Application of AlGaAs/GaAs superlattice for negative-differential-resistance transistor

ABSTRACTA novel functional resonant—tunneling bipolar transistor (RBT) has been fabricated and demonstrated. In the proposed device, electrons are injected from emitter to base by resonant—tunneling through the minibands in the i—AlGaAs/n—GaAs superlattice. The mainfeature of the proposed device is the significant double negative—differential—resistance (NDR).Two high peak—to--valley current ratios of 4: 1 and 2.6: 1 were obtained at 77K. In the transistoroperation, a common—emitter current gain of over 60 and a collector ofset voltage smaller than O.2V at 77K were obtained. As control base current increases sufficiently to cause the base—emitter junction drop beyond flat—band condition, two different transistor action regions with smaller current gains of 38 and 35 are found, respectively. Furthermore, the first peak current is nearly equal to the second peak current and much larger than the second valley current.therefore, it is attractive to exploit the device in multiple—valued logic circuits and frequencymultiplier.1. INTRODUCTIONPioneering work on resonant—tunneling through a heterostructure quantum well was firstdone by Tsu and Esaki' and Chang et al.2 However, the observed negative—differential—resistanceeffects were too small to be useful in device applications. Recently, the remarkable progress in

Microwave multiple-state resonant tunneling bipolar transistors

Fabrication and microwave performance of a multiple-state resonant-tunneling bipolar transistor (RTBT) are presented. This transistor exhibits a maximum DC current gain of 60 at room temperature and a cutoff frequency of 24 GHz. Frequency multiplication by a factor of five has been demonstrated with a single transistor. >

Multiple-state resonant-tunneling bipolar transistor operating at room temperature and its application as a frequency multiplier

A resonant-tunneling bipolar transistor with two peaks in the direct as well as in the transfer characteristics is presented. The multiple peaks are obtained by sequentially quenching resonant tunneling through the ground states of a series of double-barrier quantum wells, placed in the emitter of a Ga/sub 0.47/In/sub 0.53/As-Al/sub 0.48/In/sub 0.52/As bipolar transistor, thus obtaining nearly equal peak currents and peak-to-valley ratios. The transistor exhibits current gain of about 70 at room temperature and 200 at 77 K. Peak-to-valley current ratios at room temperature and at 77 K are as high as 4:1 and 20:1, respectively. Frequency multiplication by factors of three and five has been demonstrated using the multiple-peak transfer characteristics of the transistor. >

Quantum-well resonant tunneling bipolar transistor operating at room temperature

The first resonant tunneling bipolar transistor (RBT) is reported. The AlGaAs/GaAs wide-gap emitter device, grown by molecular beam epitaxy (MBE), contains a GaAs quantum well and two AlAs barriers between the emitter and the collector. In the common emitter configuration, when the base current exceeds a threshold value, a large drop in the collector current (corresponding to a quenching of the current gain β) is observed at room temperature, along with a pronounced negative conductance as a function of the collector-emitter voltage. These striking characteristics are caused by the quenching of resonant tunneling through the double barrier as the conduction band edge in the emitter is raised above the bottom of the first quantized subband of the well. Single-frequency oscillations are observed at 300 K. The inherent negative transconductance of these new functional devices is extremely valuable for many logic and signal processing applications.