The optical response of InAlAs/InGaAs HEMT's under illumination with modulated light from a 1.3-/spl mu/m semiconductor laser diode onto the backside of the substrate is measured by using an optical-signal analyzer. It is clear that the response is composed of two signals. One signal is dominant at a low frequency and is due to the photovoltaic effect that causes excess holes photogenerated in the InGaAs channel to accumulate in the source region. This accumulation thus causes a decrease in the threshold voltage of the HEMTs. To explain this mechanism, a theory is given which connects the change in threshold voltage with that in the Fermi energy of the two-dimensional electron gas (2-DEG). The other signal is dominant at a high-frequency and is due to the photoconductive effect in the InGaAs channel beneath the gate. In this case, a large optical gain is produced since electrons at the source region are replenished in the gate channel. This leads to the first clear observation of a photoconductive signal. The bandwidth due to the photovoltaic effect is as low as 45 MHz and is dominated by the lifetime of the excess holes. The bandwidth due to the photoconductive effect is as high as 37 GHz and is dominated by the gain-bandwidth product of transistors rather than the intrinsic transit-time of electrons.

Characteristics of InAlAs/InGaAs high-electron-mobility transistors under illumination with modulated light

This paper demonstrates an illuminated FET model including an illumination-intensity parameter for simulation of optical characteristics of microwave and millimeter wave integrated circuits (MMIC's). Modeling for an illuminated GaAs MESFET and an InP high electron-mobility transistor (HEMT), and analysis and experimental results from optically controlled microwave and millimeter-wave hybrid integrated circuit (HIC) and MMIC oscillators are discussed. The proposed illuminated FET model was able to explain the photoresponse of both the GaAs MESFET and the InP HEMT, and the photooperation of their circuits.

A novel FET model including an illumination intensity parameter for simulation of optically controlled millimeter-wave oscillators

This paper demonstrates the characteristics of the novel structure of photonic HEMT and the optical tuning characteristics of the MMIC oscillator using novel HEMT. The novel HEMT has an optical absorption layer to increase the photo-response. The fabricated oscillator consists of a InP HEMT and a CPW. The optical frequency shift of the InP MMIC oscillator using novel HEMT with 1.5 /spl mu/m optical source was 180 MHz around 37 GHz. It was found that enhancement of the optical tuning with the 1.5 /spl mu/m laser can be realized using a HEMT with novel structure.

http://ieeexplore.ieee.org/iel5/6330/16934/00780323.pdf

Characteristics of optically controlled oscillator using InP HEMT with novel structure

This paper describes the experimental results of the optically controlled InP based MMIC oscillator with illumination from the back side of the wafer. The oscillator consists of the InP HEMT and the CPW. The optical frequency shift of the InP MMIC oscillator illuminated from the front side and the back side with 1.5 μm optical source were 28 MHz and 46 MHz around 38 GHz, respectively. It was found that enhancement of the optical tuning with the 1.5 μm laser can be realized by the illumination from the back side of the InP substrate.

Optical Tuning of CPW InP MMIC Oscillator by Illumination from Back Side of Substrate Using 1.5 μm Semiconductor Laser

Modeling, design, and analysis of the illuminated MESFET and the illuminated HMIC oscillator by simulator

This paper describes modeling for an illuminated self-aligned GaAs MESFET with nonlinear parameters and experimental evaluation of an FET oscillator with non-modulated, CW and pulse signal illumination for optical control, injection locking and digital signal communication

http://ieeexplore.ieee.org/iel4/5322/14483/00662152.pdf

E. Sano

Papers

A simple microwave oscillator photodetector operating with optical signals designed by an illuminated FET model