Guoxuan Qin

RF Characterization of Gigahertz Flexible Silicon Thin-Film Transistor on Plastic Substrates Under Bending Conditions

This letter presents fabrication of a flexible 1.5-μm -channel-length silicon thin-film transistor (TFT) on a plastic substrate with a cutoff frequency fT of ~ 3.7 GHz and a maximum oscillation frequency fmax of ~ 12 GHz. Radio-frequency (RF) characterization is conducted for the flexible TFT under uniaxial mechanical bending conditions, indicating slight but notable monotonic performance enhancement with larger bending strains. Equivalent circuit model and theoretical analysis are employed to understand the underlying mechanism. Flexible gigahertz TFTs are shown to be naturally suitable for high-performance RF/microwave applications under mechanical bending (deformation) environment. This letter provides insight on designing and employing flexible gigahertz active devices.

Fabrication and Characterization of Flexible Microwave Single-Crystal Germanium Nanomembrane Diodes on a Plastic Substrate

This letter presents the fabrication and characterization of flexible microwave p-intrinsic-n diodes on a plastic substrate employing single-crystal germanium (Ge) nanomembranes. The fabricated flexible device displays high frequency response (e.g., insertion loss smaller than 1.5 dB and isolation larger than 10 dB at frequencies up to 10 GHz). Flexible Ge diodes with various diode structures are modeled and reveal radio frequency (RF) performance tradeoff with device parameters. Furthermore, the flexible Ge diodes show better RF/microwave properties than the flexible Si diodes. The study demonstrates great potential of using flexible active/passive components based on single-crystal Ge nanomembrane for high-performance RF/microwave applications.

A high gain fully integrated CMOS LNA for WLAN and Bluetooth application

In this paper a 1.8 V, 2.4 GHz CMOS fully integrated low noise amplifier (LNA) has been implemented in 0.18 μm RF CMOS process for Wireless Local Area Net (WLAN) and Bluetooth band. Acceptable consumption with higher voltage and power gain are achieved using traditional cascode configuration. In this configuration, we successed to have a good trade off among noise, gain, and stability. In order to achieve good input matching for narrow bandwidth the inductive source degeneration LNA topology is used. The LNA power gain is 22.1 dB, noise figure is 1.47 dB and the power consumption is 11 mW from a single 1.8 V power supply.

The fabrication and characterization of flexible single-crystalline silicon and germanium p-intrinsic-n photodetectors on plastic substrates

The flexible photodetector is the essential device for many of the optoelectronic applications and its performance can be influenced by a number of factors, including semiconductor materials, illumination conditions, device structures, etc. Therefore, in order to better design and use the flexible photodetectors, it is necessary to understand how these factors affect their performance. In this study, we fabricated flexible lateral p-intrinsic-n photodetectors formed with single-crystalline silicon and germanium nanomembranes on polyethylene terephthalate substrates. The performance of the flexible photodetectors with various dimensions is presented under different illumination conditions. The influences of different semiconductor materials, illumination conditions (wavelength and power of the incident light), and dimensions of the intrinsic region (length and width) on the photocurrent and efficiency are investigated, and the underlying mechanisms are studied based on experimental, simulation, and theoret...

On the bending characterization of flexible radio-frequency single-crystalline germanium diodes on a plastic substrate

Mechanical bending characterizations are performed on flexible radio-frequency (rf) single-crystalline germanium (Ge) diodes on plastic substrates. Transversal and longitudinal, convex, and concave bendings are conducted. Dc and rf experimental results indicate different performance dependence of the diodes on different types of bending strains, at different biases. Equivalent circuit model is employed to analyze the underlying mechanisms that affect the characteristics of the flexible Ge diodes under bending conditions. Less performance variations are observed for the flexible Ge diodes than the Si diodes with bending strains. The flexible single-crystalline Ge diodes demonstrate good high frequency response and robustness for mechanical bendings.

Dc characteristics of proton radiated SiGe power HBTs at cryogenic temperature

The dc performances of proton irradiated silicon-germanium (SiGe) power heterojunction bipolar transistors (HBTs) at cryogenic temperature are reported in this work. Large emitter area high-power SiGe HBTs fabricated in a commercial BiCMOS process were irradiated with proton, at different fluences from 1×1012 p/cm2 to 5×1013 p/cm2. We show that proton radiated SiGe power HBTs are naturally suitable for electronic operations at cryogenic temperature. Specifically, investigation of proton radiation on SiGe power HBTs at liquid nitrogen temperature (77K) indicates a significant potential for space applications. The results demonstrate the potential of SiGe power HBTs in power amplification for wireless applications under severe radiation and extreme temperature environment (cryogenic) even without any intentional radiation hardening.

Influence of collector region design on SiGe power HBT linearity characteristics

The influence of collector region design (used to realize different breakdown voltages) on the linearity characteristics of SiGe power HBTs is investigated experimentally via the measurements of third order intermodulation distortion (IMD3). It is shown that collector doping concentration has significant influence on devices characteristics. SiGe power HBTs with higher collector doping concentration exhibit both better linearity characteristic and better RF power performance than the low collector doping concentration HBTs.

Characterization of flexible radio-frequency spiral inductors on a plastic substrate

This paper describes the design and fabrication of flexible radio-frequency inductors integrated on a polyethylene terephthalate substrate. Experimental and modeling results for the RF responses of flexible inductors are reported. Investigations and analysis have been conducted on the effects of layout and process parameters on the frequency responses of inductance, quality factor and self-resonant frequency of the spiral inductors. The influence of bending strain on the performance of spiral inductors is also investigated based on measurement and modeling results. The analysis provides guidelines for designing the flexible spiral inductors towards the flexible monolithic microwave integrated circuits on a plastic substrate.

Fabrication, characterisation and modelling of fast flexible semiconductor nanomembrane electronics

The novel properties of micro- and nanomembranes (e.g., flexible, stretchable, transferable, lightweight, capability of covering large area) offer great opportunities for a variety of new applications in electronics, photonics, microelectromehanical systems (MEMS), and other areas. This paper reviews the material fabrication and representative transfer techniques of nanomembranes for versatile functionalities. Characterisation and modelling of fast flexible nanoelectronics are reviewed: from individual devices such as thin-film transistors, diodes to circuits such as RF switches. This paper provides an overview of the fast flexible nanoelectronics based on transferable nanomembranes and indicates possible directions of semiconductor nanomembranes for exciting new science and nanotechnology.

Status overview: Fabrication, characterization and modeling of flexible RF/microwave nanoelectronics

Flexible nanoelectronics have drawn increasing attention over the past few years, for their unique properties such as bendable, reliable or foldable, can conformai attached to any shape of surfaces, light weight, etc. The device speed of flexible nanoelectronics has been increasing and reached RF/microwave regime as new fabrication/design techniques are developed. In order to provide design guidelines of employing these fast flexible nanoelectronics for flexible microwave monolithic integrated systems, characterization and modeling works have been conducted. This paper briefly reviews the recent development on fabrication, characterization and modeling for flexible RF/microwave nanoelectronics.