K. Onda

InAlAs/InGaAs channel composition modulated transistors with InAs channel and AlAs/InAs superlattice barrier layer

We have successfully fabricated a new type of InAlAs/InGaAs heterojunction FET (HJFET) with modulated indium composition channels, called channel composition modulated transistors (CCMTs) in which an InAs channel is sandwiched by In/sub 0.53/Ga/sub 0.47/As/In/sub 0.8/Ga/sub 0.2/As sub-channels. The fabricated devices also employ an AlAs/InAs superlattice as a barrier layer against impurity contamination to provide high thermal stability. A 0.2-/spl mu/m T-shaped gate device exhibits a g/sub m/ of 1370 mS/mm, F/sub t/ of 180 GHz and F/sub max/ of 210 GHz at a low drain bias of 1.0 V. In high-temperature DC life tests conducted at more than 230/spl deg/C, the devices exhibited less than a 3% degradation in I/sub dss/ and g/sub m/ after 1000 h. This demonstrates that these newly-developed CCMTs incorporating AlAs/InAs superlattice insertion technology can offer high-performance and highly-reliable InP-based HJFETs for various microwave and millimeter-wave applications.

Electrical properties of InAlAs/InGaAs modulation doped structure after SiN passivated annealing

The effect of thermal annealing on the InAlAs/InGaAs modulation-doped structure, passivated with a SiN film, was investigated. In contrast to the capless sample, the passivated modulation-doped sample exhibited negligible degradation in the two-dimensional electron gas concentration (NS) after annealing at 280 °C, indicating that SiN is an efficient passivation material to ensure good thermal stability for the InAlAs/InGaAs modulation-doped structure. In addition, partial recovery in NS was found by annealing the SiN-passivated sample that had experienced serious NS degradation. A series of secondary ion mass spectroscopy (SIMS) measurements and Hall effect measurements revealed that the recovery of NS is associated with the discharge of fluorine atoms from the Si-doped n-type InAlAs layer.

Manufacturable and reliable millimeter wave HJFET MMIC technology using novel 0.15 /spl mu/m MoTiPtAu gates

This paper describes a manufacturable and reliable millimeter-wave heterojunction FET (HJFET) MMIC technology, in which a novel 0.15 /spl mu/m MoTiPtAu T-shaped gate has been successfully employed. Excellent DC and RF device characteristics, including Imax of /spl sim/600 mA/mm, BVgd of >10 V and Fmax of /spl sim/200 GHz, were confirmed. High temperature DC-bias tests predict an MTTF of 1.5/spl times/10/sup 7/ hours at a channel temperature of 150/spl deg/C. The 2-stage MMIC amplifier, fabricated using the developed technology, exhibited a 69.5 mW output power with 14.4% power-added efficiency at 56 GHz with good uniformity.<<ETX>>

A K-band monolithic CPW oscillator co-integrated with a buffer amplifier

This paper describes the design approach, fabrication process, and performance of a monolithic CPW oscillator incorporating a buffer amplifier on the same chip, for K-band wireless network applications. At 21 GHz, the output power of the oscillator recorded 17 dBm with an overall DC-RF efficiency of 22%. By changing the length of a source feedback line, the oscillation frequency was varied up to 26 GHz. For all cases, the output power remained higher than 16 dBm.<<ETX>>

Fluorine diffusion and accumulation in Si step-doped InAlAs layers

The quantitative relation between fluorine (F) accumulation and Si donor concentration in n-InAlAs layers on InP substrate was investigated for several kinds of step-doped InAlAs samples using secondary ion mass spectroscopy. From the depth profile of F and Si donors in a periodic i-/n-InAlAs sample, we found that F accumulates only in n-InAlAs layers, passing through i-InAlAs layers. We also found that the amount of F accumulation in an n-InAlAs layer depends on the Si doping concentration. The experimental results can be explained by considering two states of F. In one state, F is bound to a Si donor and immobile, and in the other it is free and can diffuse.

Fluorine diffusion in step-doped InAlAs layers on InP substrate

The quantitative relation between fluorine (F) accumulation and Si donor concentration in n-InAlAs layers on InP substrate was investigated for several kinds of step-doped InAlAs samples using secondary ion mass spectroscopy. From the depth profile of F and Si donor in a periodic i-/n-InAlAs sample, we found that F accumulates only in n-InAlAs layers, passing through i-InAlAs layers. Also, we found that the amount of F accumulation in an n-InAlAs layer depends on the Si doping concentration. The experimental results can be explained by considering two states of F. In one state, F is bound to a Si donor and immobile, and in the other it is free and can diffuse.

InP-based heterojunction FET processing for high-reliability millimeter-wave applications

Describes a novel InP-based FET processing technology for high-reliability microwave applications. High performance InAlAs/InGaAs heterojunction FETs (HJFETs) were fabricated using completely molybdenum-based electrode technology (COMET). The fabricated 1 /spl mu/m gate-length COMET-HJFET exhibited excellent DC and RF performance, including a transconductance of 470 mS/mm and a current gain cutoff frequency of 40 GHz. High temperature DC bias tests performed on the COMET device demonstrated improved reliability compared to that for the conventional InP-based HJFET. The superior reliability of the developed COMET-HJFET is attributed to the reduced interdiffusion between metals of the electrodes and semiconductors by introducing a refractory metal of Mo as a barrier metal.

Novel InAlAs/InGaAs heterojunction FETs with modulated indium composition channel and AlAs/InAs superlattice barrier layer

Novel InAlAs/InGaAs heterojunction FETs (HJFETs) with modulated indium composition channels, named CCMTs (Channel Composition Modulated Transistors), have been successfully fabricated, in which an InAs channel is sandwiched by In/sub 0.53/Ga/sub 0.47/As/In/sub 0.8/Ga/sub 0.2/As sub-channels. The channel structure is designed to improve electron transport and electron confinement by increase effective indium content in consideration of channel electron distribution. The fabricated devices also employ an AlAs/InAs superlattice as a barrier layer against impurity contamination for high thermal stability. A 0.2 /spl mu/m T-shaped gate device exhibits gm of 1370 mS/mm, and Ft of 180 GHz at a low drain bias of 1.0 V. In high temperature and DC life test conducted at more than 230/spl deg/C, the devices exhibited less than 3% degradation after 100 hrs, which shows the developed CCMTs with AlAs/InAs superlattice insertion technology can offer high-performance and highly-reliable InP-based HJFETs for various microwave and millimeter-wave applications.

V-band monolithic integrated circuits for personal communication terminals

A single-stage high gain wide band amplifier and an MMIC oscillator at V-band have been successfully fabricated based on a 0.15 micrometers T-shaped gate AlGaAs/InGaAs/AlGaAs heterojunction FET (HJFET) technology. The MMIC amplifier exhibits 7.2 dB +/- 1.0 dB gain over 49 approximately equals 61 GHz band and 15.3 dBm output power at 57.9 GHz. The MMIC oscillator shows 51 GHz oscillation with 2.8 dBm output power. These MMICs are promising for realizing compact personal communication terminals.