Luhong Mao

CMOS-NDR transistor

In this paper, a novel device - MOS-NDR transistor is proposed and fabricated which is composed of four N-channel metal-oxide-semiconductor field effect-transistor (NMOS) devices. This MOS-NDR transistor could exhibit the negative differential resistance (NDR) characteristics similar to the conventional NDR device such as compound material based RTD (resonant tunneling diode) in the current-voltage characteristics by suitably modulating the MOS parameters, at the same time it could realize good modulation effect by the third terminal and has advantages of low working voltage (peak voltage Vp=0.7 V) and high PVCR (Peak to Valley Current Ratio) (nearly 10:1). The design and fabrication of this device are completely compatible with the standard 0.35 ¿m CMOS process, thus can considerably extend the functions of the CMOS circuits into new scope.

Monostable–Bistable Transition Logic Element Formed by Tunneling Real-Space Transfer Transistors With Negative Differential Resistance

We demonstrate three-terminal λ-type negative differential resistance (NDR) tunneling real-space transfer transistors (TRSTT) with InGaAs and a δ-doped GaAs dual-channel structure on a (100) GaAs substrate. The NDR mechanism is attributed to the electron tunneling transfer from a high-mobility InGaAs channel to a low-mobility δ-doped GaAs channel, as well as to a gate electrode through a Schottky cap layer. The maximum of the peak-to-valley current ratio and the transconductance of the peak current density (<i>g</i>_m = Δ<i>J</i>_P/Δ<i>V</i>_GS) reach 3.3 and 72 mS/mm, respectively. The invert operation of MOBILE is realized by employing two TRSTTs connected in series at room temperature.

Fabrication and DC current-voltage characteristics of real space transfer transistor with dual-quantum-well channel

We reported the standard ¿¿¿ shape negative differential resistance as well as a level and smooth valley region in real space transfer transistor (RSTT) with dual-quantum-well channel, which are formed by ¿-doping GaAs quantum-well and InGaAs/GaAs heterojunction quantum-well. The highest peak-to-valley current ratio (PVCR) of RSTT reaches 4 at room temperature. The highest peak current density transconductance (¿JP/¿VGS) is 130 ms/mm, which demonstrates the control ability of gate to JP. The mechanism of obvious NDR of RSTT can be explained that the hot electron in the InGaAs U-shaped quantum-well channel transfers into V-shaped ¿-doping GaAs quantum-well channel, and the hot electron transfers into gate electrode from V-shaped ¿-doping GaAs quantum-well channel. This novel NDR device would be expected to applied in NDR circuits to instead of RTD+HEMT.

NDR Heterojunction Bipolar Transistor with Base of 8nm Width

The high performance Negative differential resistance n-InGaP/P-GaAs/n-InGaP heterojunction bipolar transistor with base of 8nm width has been designed and fabricated successfully. The fabricated device exhibited voltage and current controlled two different negative resistance I-V characteristics for a same device and also exhibited a similar NDR characteristics related with transition from bipolar transistor to bulk barrier transistor. In this paper, above two special properties of NDRHBT have been investigated and analyzed

Simulation of bipolar/MOSFET hybrid mode transistor with Si/GeSi heterojunction base

Bipolar/MOSFET hybrid mode lateral transistor is a transistor in which both bipolar and MOSFET currents flow simultaneously. Because of (1) Good compatibility with CMOS technology; (2) Larger current driving capability and transconductance than MOSFET. So, it is suitable to be taken as a bipolar device in BiCMOS element. In this paper, the Si/SiGe heterostructure, under the gate, is introduced into the conventional bipolar/MOSFET hybrid mode transistor. So a hybrid mode transistor with a lateral n+-Si/p-SiGe/n+-Si structure parallel in base is formed, in which the heterostructure of E-B junction n+-Si/p-SiGe has a high injection electron current from E to B region and a low injection hole current from B to E region (result in by higher barrier for hole), then the total injection efficiency will increase. When this effect becomes a main mechanism than that of the barrier lowering in the surface depletion layer, the characteristics of the device will be dependent on the parameters of SiGe alloy, such as the mole number of Germanium etc. The device simulation of Si/SiGe heterojunction base hybrid mode transistor has been carried out by MEDICI program. The simulation results show that IC and hFE increase with Mole number of Ge increasing and WB decreasing, then the current gain and current capability are improved than that of conventional bipolar/MOSFET hybrid Mode transistor.