Guo Weilian

Study on resonant tunneling diode

We designed and fabricated an AlAs/GaAs/InGaAs/GaAs/AlAs Resonant Tunneling Diode (RTD) with two types of epitaxial structures grown by Molecular Beam Epitaxy (MBE). The devices have shown excellent I-V characteristics with peak-valley current ratio (PVCR) 5:1 at room temperature and a high peak current density. The DC and AC characterizations are reported and analyzed.

Manufacture of SiGe HMOSFET

The advances in the growth of pseudomorphic silicon-germanium epitaxial layers combined with the strong need for high-speed devices have led to increased interest in silicon-based heterojunction field-effect transistors. Here we present a kind of strained SiGe-channel P-MOSFET which can offer better performance compared to the Si device. When applying to the sample with W/L value of 14/7, a 30% improvement can be achieved in transconductance.

Effect of ICP etching on InP-based multiple quantum wells microring lasers

Dry etching of InP-based epitaxial structure was performed by using inductively coupled plasma (ICP) system with different chemistries. The surface topographies shown that the waveguide profiles etched using the Cl2/CH4/Ar recipe have better surface and sidewall quality than that of the Cl2/BCl3 chemistry. To verify the practical influence of ICP etching, InP/AlGaInAs multiple quantum wells microring lasers were fabricated, and the electrical and optical properties were compared. The experimental results revealed that the Cl2/CH4/Ar recipe is preferable to the fabrication of InP-based optoelectronic devices in our experimental system.

AlGaN-based solar-blind metal-semiconductor-metal photodetectors

We reported on the fabrication and characterization of AlGaN metal-semiconductor-metal (MSM) photodetectors (PDs). AlGaN epitaxial material with an Al content of 0.6 were grown on sapphire substrates by metalorganic chemical vapor deposition (MOCVD). Schottky contacts were made with Ni/Pt/Au by the way of standard lift-off technique. We measured the performance of PDs. The cutoff wavelength is 276nm. Ultraviolet/visible contrast is about 3 orders of magnitude. The dark current is about 1nA at 1.5V bias and 1µA at 5.3V bias.

Design and Testing of a Si-LED based on CMOS Technology

In this paper,a Si-LED was designed and manufactured with CSMC 0.5 μm CMOS Technology which could emit two different kinds of light at both forward bias mode and reverse bias mode.At room temperature,the characteristics of the device were primarily tested.It could be turned on at forward bias of 0.7 V and at reverse bias of 7.5 V.The device structure was adopted with the layer P-base and n+,and the two overlaps forming Si-pn junction LED.The Si LEDs emitting micrographs and real layouts were captured by an Olympus IC microscope,and emission spectra of Si LED was presented.At the forward bias mode,this device emitted infrared light and the emitting peak value was located at 1 125 nm.At the reverse bias mode,this device emitted visible light,its emitting peak value was about at 725 nm.

Study on novel voltage controlled oscillator

A novel voltage controlled oscillator (VCO) without inductances has been fabricated for the first time based on dual base transistor (DUBAT), which is normally considered as a negative resistance device. The physical model gained through the analysis of the two dimensional transportation of its internal charge carriers of this oscillator is described in detail and its equivalent circuit is introduced. The results simulated by SPICE are consistent with those of experiments. An excellent linearity of frequency versus control voltage is realized with a custom voltage range of control electrode. The simplicity of DUBAT structure and the compatibility of bipolar integrating process make this novel VCO a promising candidate for combination of VCO with functional circuits on a single silicon chip.

Design and simulation of SiGe channel SOI BMHMT

We address the integrated circuit, adopting SOI (silicon on insulator) structure with SiGe channel BMHMT (Bi-MOS hybrid-mode transistor). It has dynamic threshold voltage and is fit for working at low supply voltage conditions. We have performed the process and device simulation of SiGe channel SOI BMHMT and made comparison with SiGe channel SOI MOSFET and SOI MOSFET. Simulation results show that in terms of p-channel and n-channel device, the driving capabilities of SiGe channel SOI BMHMT are obviously higher than those of SiGe channel SOI MOSFET and SOT MOSFET and the improvement on n-channel device is more obvious.

Small signal equivalent circuit model of vertical cavity surface emitting lasers

A small signal equivalent circuit model of vertical cavity surface emitting lasers (VCSELs) is given in this paper. The modulation properties of the VCSEL are simulated using this model in the Pspice program. The simulation results are in good agreement with experimental data. An experiment is performed to testify the circuit model.

The voltage controlled current bistability (VCCB) in DUBAT

In this paper the voltage controlled current bistability (VCCB) hysteresis loop has been found in the I/sub C/-V/sub BE/ characteristics for the DUal BAse transistor (DUBAT). The ratio of high current to low current (R) is 945 and the width of bistability loop is 3.38 V. The minimum rise time t/sub /spl tau// of VCCB is near 40 ns. It is possible that VCCB of DUBAT can be used to make a Static Random Access Memories (SRAM) cell in the near future.