N-shaped Negative Differential Resistance Research Articles

Enhanced resonant tunneling real-space transfer in δ-doped GaAs/InGaAs gated dual-channel transistors grown by MOCVD

We report the observation of pronounced N-shaped negative differential resistance (NDR) and negative transconductance at high drain and gate fields in /spl delta/-doped GaAs/InGaAs gated dual-channel transistors (DCTs) by tunneling real-space transfer (TRST). By virtue of varying the sheet density of the /spl delta/-doping layer as well as the thickness of the GaAs barrier, pronounced multiple-state NDR characteristics were obtained accompanying the gate current characteristic at room temperature. A peak-to-valley current ratio (PVR) of 15 was obtained which, to our knowledge, is the highest among the reported TRST devices at room temperature. The proposed devices possess potential advantages of ease of growth and fabrication.

The study of [formula omitted] δ-doping resonant interband tunneling diode

The δ-doping InGaAs GaAs quantum well resonant interband tunneling diode by low pressure metal organic chemical vapor deposition has been successfully grown. The full width at half maximum of the doping profile analyzed by capacitance-voltage measurement is small. Two kinds of δ-doping resonant interband tunneling diodes were simulated in this study. One was the δn + -i-δp + resonant interband tunneling structure and the other was the δn + -i-δp + -i-δn + single barrier resonant interband tunneling structure. The simulated current-voltage characteristics exhibited the expected N-shaped negative differential resistance. The calculated peak-to-valley current ratio (PVCR) values of δn + -i-δp + and δn + -i-δp + -i-δp + structures are 6 and 5.6, respectively. The calculated PVCR value is larger than experimental PVCR values for the δn + -i-δp + structure. The PVCR values of this study are better than the published data of other authors.

Observation of the anomalous current–voltage characteristics of GaAs/n+-InGaAs/GaAs doped-channel structure

A GaAs/n+-In0.2Ga0.8As/GaAs doped-channel field-effect transistor structure has been fabricated and studied. A typical transistor performance with a threshold voltage of about −3.0 V and transconductance of up to 160 mS/mm is obtained in the lower gate-source voltage (VGS <−1.0 V) regime. However, for some devices, the three-terminal-controlled N-shaped negative-differential-resistance (NDR) behavior is observed at the saturation regime of current–voltage characteristics under higher gate-source bias (VGS≥−1.0 V) condition. The interesting NDR phenomenon is believed to be attributed to the real-space transfer and deep-level electron trapping effect.

Electrical properties of a heterojunction bipolar transistor structure with a resistive gate

A conventional heterojunction bipolar transistor with a resistive gate, formed by placing the third location in the depletion region of the collector layer instead of the base layer, is investigated. The influences of the gate voltage on the device performance then strongly depend on the applied voltage. The results show that the device operated under voltage-controlled mode exhibits novel N-shaped negative differential resistance (NDR) characteristics, which have large room temperature NDR peak-to-valley current ratios (e.g. 140 at a gate bias of 1.5 V) and large voltage extension in N-shaped NDR region (about 9 V). However, the device exhibits the transistor characteristics with the current gain of 4 under current-injected mode. The above discrepancies between voltage-controlled and current-injected modes are attributed to the existence of the resistive gate.

GaAs-InGaAs quantum-well resonant-tunneling switching device grown by molecular beam epitaxy

In this letter, a new switching device having a p-type delta-doped sheet in the center of an InGaAs-GaAs quantum well is presented. An N-shaped negative-differential-resistance (NDR) phenomenon resulting from the resonant tunneling effect through the miniband under a proper anode-to-cathode voltage is observed. From the experimental results, it is seen that the temperature plays an important role in the device operation.

Self-generated nonlinear oscillations in multilayer semiconductor heterostructures

Nonlinear charge transport parallel to the layers of modulation-doped GaAs/AlxGa1-xAs heterostructures is studied theoretically and experimentally. In the field regime of about 2 kV cm-1 we find DC-induced current oscillations associated with N-shaped negative differential resistance. We develop a dynamic model based on real space transfer of hot electrons from the undoped high-mobility GaAs layers to the adjacent n-doped low-mobility AlxGa1-xAs layers. In particular, we extend previous models to multilayer structures and investigate the dependence of the self-generated oscillations upon circuit conditions and the lattice temperature in the range TL=77-200 K. In the light of the experimental results the theoretical predictions are analysed and discussed.

N-shaped negative differential resistance in a transistor structure with a resistive gate

Voltage-controlled negative differential resistance (NDR) characteristics in a N-AlGaAs/p/sup +/-GaAs/n-GaAs transistor structure are proposed and demonstrated. The gate, made using self-aligned p-type diffusion, is placed in the n-GaAs collector layer instead of the p/sup +/-GaAs base layer, resulting in a so-called resistive gate. For a fixed gate voltage, the device current is modulated by the applied anode voltage. Under appropriate gate voltage with respect to the anode, the device shows good voltage-controllable NDR characteristics, including large peak-to-valley current ratios (PTV's) and a voltage extension in the N-shaped curve which is equivalent to the common-emitter breakdown voltage in a transistor. A numerical model based on the transistor model for the carrier transport in this device, taking account of the influence of the applied anode voltage on the gate, is proposed. The experimental results show large room temperature PTV's (e.g., 140 at a gate bias of 1.5 V) and large voltage extension in N-shaped curves (about 9 V). Reasonable agreement between theoretical and experimental results is observed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Application of a triple-well superlattice emitter structure to GaAs switching device

A new GaAs switching device with a triple-well superlattice emitter structure, prepared by molecular beam epitaxy, has been fabricated and demonstrated. An S- and N-shaped negative-differential-resistance (NDR) phenomenon, attributed primarily to the avalanche multiplications process and resonant-tunneling effect, were observed simultaneously when a proper collector-emitter voltage (VCE) was applied. The operation temperature is known from the experimental results to play an important role on the influence of the NDR behaviors. A transistor action with a common-emitter current gain of over 36 was also achieved at 300 K when a control current was employed to the base electrode. This device exhibited a significantly regenerative switching phenomenon both at room temperature and low temperature if a −VCE voltage was used. The proposed structure consequently has good potential for switching and quantum functional device applications.

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.

Investigation of heterostructure-confinement-emitter transistors

In this paper we review our current investigation on heterostructure-confinement-emitter transistors, i.e. heterostructure-emitter bipolar (HEBT) and superlattice-emitter (SET), and then describe further advances in negative-differential-resistance (NDR) devices just utilizing GaAs-based materials. An improved HEBT using an Al 0.5Ga 0.5As as a confinement layer exhibits not only a common-emitter current gain of 180 but also a very small offset voltage of 80 mV when operated under a normal mode, which is much better than for a Al 0.3Ga 0.3As confinement layer. An S-shaped NDR phenomenon is observed when operating under reverse mode. On the other hand, instead of an AlGaAs bulk layer, a five-period AlGaAs/GaAs superlattice is employed as a confinement and tunneling barrier for the SET device. Experimentally, a common-emitter current gain of 65 (maximum of 95 at 300 K) and double N-shaped NDR performance with peak-to-valley ratios (PVRs) of 4 and 2.6 are obtained at 77 K. These discussions are followed by theoretical considerations and experimental analyses. It is found that the new devices studied are of considerable interest for a variety of potential applications that could be realized with greatly reduced circuit complexity.

Observation of N- and S-shaped negative differential resistance behavior in AlGaAs/GaAs resonant tunneling structure

A MBE-grown two-terminal GaAs device with AlGaAs/GaAs quantum wells embedded in the base of a heterojunction bipolar transistor structure exhibiting both S-shaped and N-shaped negative differential resistance (NDR) characteristics is demonstrated. Due to the asymmetric structure, both S-and N-shaped NDR behaviors can be observed in the same device depending on the polarity applied. The S-shaped NDR behavior is explained by the enhancement of an avalanche process while the N-shaped NDR characteristics is attributed to a resonant tunneling process. The effects of band offset of AlGaAs/GaAs in the emitter/base and/or base/collector junction are found to have profound influence on the device characteristics and will be discussed.

Switching effect based on the N-shaped negative differential resistance in n-CdCr2Se4 single crystals

physica status solidi (a)Volume 80, Issue 2 p. K149-K151 Short Note Switching effect based on the N-shaped negative differential resistance in n-CdCr2Se4 single crystals K. G. Nikiforov, K. G. Nikiforov Institute of Applied Physics, Academy of Sciences of the Moldavian SSR, Kishinev Search for more papers by this authorV. P. Buzhor, V. P. Buzhor Institute of Applied Physics, Academy of Sciences of the Moldavian SSR, Kishinev Search for more papers by this authorS. I. Radautsan, S. I. Radautsan Institute of Applied Physics, Academy of Sciences of the Moldavian SSR, Kishinev Search for more papers by this authorV. E. Tezlevan, V. E. Tezlevan Institute of Applied Physics, Academy of Sciences of the Moldavian SSR, Kishinev Search for more papers by this author K. G. Nikiforov, K. G. Nikiforov Institute of Applied Physics, Academy of Sciences of the Moldavian SSR, Kishinev Search for more papers by this authorV. P. Buzhor, V. P. Buzhor Institute of Applied Physics, Academy of Sciences of the Moldavian SSR, Kishinev Search for more papers by this authorS. I. Radautsan, S. I. Radautsan Institute of Applied Physics, Academy of Sciences of the Moldavian SSR, Kishinev Search for more papers by this authorV. E. Tezlevan, V. E. Tezlevan Institute of Applied Physics, Academy of Sciences of the Moldavian SSR, Kishinev Search for more papers by this author First published: 16 December 1983 https://doi.org/10.1002/pssa.2210800245Citations: 1 Akademicheskaya 5, 277028 Kishinev, USSR. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume80, Issue216 December 1983Pages K149-K151 RelatedInformation