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We report a comprehensive etching study on the gate recess step for the fabrication of the novel high speed pHEMT devices. The experiments focused on the elimination of “hump” structure as a result of an incomplete etching process at the InGaAs cap layer. In this work, two types of test samples were used, namely bulk InGaAs and epitaxial structure together with an etch stop layer. The result showed...
Linear modelling of novel InGaAs/InAlAs/InP pHEMT for low noise applications is substantial to the future transistors that will operate in high speed and low noise conditions. The novel pHEMT is constructed by sandwiching two different materials together with different lattice constants, for instance InGaAs and InAlAs in order to form a heterojunction in between. However, InP is only utilised to be...
HEMT is a GaAs based field effect transistor that retains higher cutoff frequency compared to silicon based transistors. Alternatively, pHEMT enhance the performance of the HEMT in term of leakage, current conduction and the cutoff frequency of the device. The heterostructure of pHEMT improve the performance two-dimension electron gas (2DEG) in the channel layer. With these, pHEMT is believed could...
In this work, the design of a novel low noise amplifier (LNA) based on 1μm gate-length InGaAs/InAlAs/InP pHEMT transistors is discussed. Designed for radio astronomy applications, this amplifier exploits a common drain configuration as an input stage and a common source inductive degeneration topology as an output stage. It exhibits a maximum gain of 30 dB within an input 1-dB compression point of...
A series of room temperature operating double stage differential to single-ended MMIC low noise amplifiers (LNA) design are presented in this work and are based on novel high breakdown InGaAs/InAlAs/InP pHEMTs that have been developed and fabricated at the University of Manchester. All designs are optimised for the frequency range of 0.3 to 1.4GHz in line with the Square Kilometre Array (SKA) requirements...
This paper presents a Novel low noise, high breakdown InAlAs/InGaAs pseudomorphic High Electron Mobility Transistors (pHEMTs). The improvements in breakdown voltage are brought about by a judicious combination of epitaxial layer design and field plate techniques. No significant degradations of DC and RF characteristics are observed for devices with field plate structures. An outstanding improvement...
The InAlAs/InGaAs material system provides one of the highest transconductance pHEMT devices at a given gate size because of its large conduction band discontinuity, high electron mobility and very good carrier confinement in the channel. The DC characteristics, however, show a sudden rise in drain current at fixed value of drain voltage, resulting in high drain conductance and reduced voltage gain...
Linear and non-linear modelling of a novel ultra-low noise InGaAs/InAlAs pHEMTs have been used to design a low noise amplifier operating from 0.3 to 2 GHz. The LNA has ~ 0.4 dB NF across the whole frequency band, power gain of 26 dB at 1.4 GHz and IP3 of 14 dBm, making it a good candidate for the aperture array concept of the Square Kilometre Array (SKA) telescope, GSM, GPS, civil and military DAB.
This paper presents the design, fabrication and characterisation of InGaAs-InAlAs pHEMTs suitable for low frequency LNA designs. Transistors with variations in the supply layer thickness or indium concentration are designed to provide for a range of transfer characteristics. Very low levels of leakage, of order of 0.2 muA/mm, are demonstrated by these pHEMTs, which enables the implementation of large-geometry,...
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