Thermal reaction of Ti evaporated on GaAs

Mun

Journal of Applied Physics

1997

The thermal stability of Ti/Pt/Au Schottky gates on high-low doped GaAs metal-semiconductor field-effect transistors ͑MESFETs͒ was investigated in the temperature range of 300-500°C, using current-voltage and capacitance-voltage measurements and cross-sectional transmission electron microscopy with energy dispersive x-ray spectroscopy. At annealing temperatures Ͼ350°C, the interfacial reactions cause the formation of a layered structure of Ti/Ti-Ga/Ti-As/GaAs. The depth distribution of electron concentration moves toward the Ti/GaAs interface as the annealing temperature increases. This is due to the growth of Ti-As, followed by the reduction of the channel thickness. The activation energy for the growth of Ti-As is determined to be 1.74 eV. The electron concentration in the channel layer decreases with the increase of the annealing temperature. This is due to the out-diffusion of Ga to the Ti film, resulting in the production of acceptor-type Ga vacancies and thereby the decrease of electron concentration in the channel. The activation energy for the reduction of electron concentration, equal to the formation energy of the acceptor-type Ga vacancies, is determined to be 1.42 eV. This is closed to the activation energy of 1.3 eV for the device failure obtained at annealing temperatures ranged from 300 to 350°C. From these observations, it is proposed that the thermal degradation of GaAs MESFETs at temperatures Ͻ350°C, mainly proceeds by the electron compensation with acceptor-type Ga vacancies in the channel, whereas it occurs by the growth of Ti-As below the original Ti/GaAs interface at temperatures Ͼ350°C.

Section: Resultssupporting

confidence: 92%

Section: Discussionsupporting

confidence: 91%

“…2. The growth of Ti-As controlled by the interdiffusion between Ti and As, which obeyed a parabolic rate law, 8 as in Eq. ͑2͒…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Thermal degradation mechanism of Ti/Pt/Au Schottky contact to n-type GaAs

Mun

Journal of Applied Physics

1997

Wiley Encyclopedia of Electrical and Electronics Engineering

Modulation‐Doped Field‐Effect Transistors (MODFET)

Zhu

Ferreyra

Morkoç̌

2015

Conventional modulation‐doped field‐effect transistors (MODFETs) with unprecedented performance, e.g., a power gain of 15 dB at 190–235 GHz and a noise level of 1.2 dB with 7.2‐dB gain in the 90‐GHz range, have been demonstrated. Passivation process is of fundamental importance in the stability, good performance, and extension of device operative lifetime. We discuss strategies used to passivate the surface of GaAs and related compounds and GaN in the context of FETs. Recent research on the enhancement‐mode PMODFET (E‐PMODFET) variety for applications in high‐speed and low‐power digital circuits, and power amplifiers with single power supply is described. Reliability of MOSFET based on GaAs is reviewed to some extent. Scalability issues as well as progress in FinFET‐based on InGaAs channel are summarized. Also to be noted is that III–V compound semiconductors as alternative to Si as the channel material to improve the performance of metal‐oxide–semiconductor field‐effect transistors (MOSFETs) on Si platforms is a very attractive option for the next‐generation high‐speed integrated circuits but faces serious challenges because of the lack of a high‐quality and natural insulator. III‐V Nitride‐based HFETs showed tremendous performance in both high‐power RF and power‐switching applications. AlGaN/GaN based high power HFETs on SiC substrate with 60 nm gate lengths have achieved maximum oscillation frequency of 300 GHz. On‐resistance of 1.1∼1.2 Ω·mm as well as drain current of ∼0.9 A/mm was also achieved. For HFET devices operated in Class AB mode on GaN semi‐insulating substrates, a continuous wave power density of 9.4 W/mm was obtained with an associated gain of 11.6 dB and a power added efficiency of 40% at 10 GHz. III‐Nitride devices for power switching application has achieved near theoretical limit for vertical devices based GaN native substrates, and breakdown voltage as high as 1200 V and on resistance as low as 9 mΩ‐cm2 for lateral HFET devices on low‐cost silicon substrates. For AlGaN/GaN HFETs on high‐resistivity silicon substrates, promising results were also demonstrated. Because of the much larger 2DEG density in lattice‐matched InAlN/GaN HFETs, drain current as high as 2 A/mm was demonstrated, and the highest current gain cutoff frequency of 370 GHz was also reported on 7.5‐nm‐thick In In0.17Al0.83N barrier HFETs. Despite the above‐mentioned encouraging achievements, the degradation mechanisms are still not clear, which requires further investigation. The advent of high‐quality SiGe layers on Si substrates has paved the way for the exploration and exploitation of heterostructure devices in a Si environment. MODFETs based on the Si/SiGe have been achieved with extraordinary p ‐channel performance. With 0.25‐μm gate lengths, the current gain cutoff frequency is about 40 GHz. When the gate length was reduced to 0.1 μm, the current gain cutoff frequency increased to about 70 GHz.

Encyclopedia of RF and Microwave Engineering

Modulation Doped FETs

Ding,

Zhu,

Ferreyra

et al. 2024

Conventional modulation‐doped field‐effect transistors (MODFETs) with unprecedented performance, for example, a power gain of 15 dB at 190–235 GHz and a noise level of 1.2 dB with 7.2‐dB gain in the 90‐GHz range, have been demonstrated. Passivation process is of fundamental importance in the stability, good performance, and extension of device operative lifetime. We discuss strategies used to passivate the surface of GaAs and related compounds and GaN in the context of FETs. Recent research on the enhancement‐mode PMODFET (E‐PMODFET) variety for applications in high‐speed and low‐power digital circuits and power amplifiers with single power supply is described. Reliability of MOSFET based on GaAs is reviewed to some extent. Scalability issues as well as progress in FinFET‐based on InGaAs channel are summarized. Also to be noted is that III–V compound semiconductors as an alternative to Si as the channel material to improve the performance of metal‐oxide–semiconductor field‐effect transistors (MOSFETs) on Si platforms are a very attractive option for the next‐generation high‐speed integrated circuits but face serious challenges because of the lack of a high‐quality and natural insulator. III‐Nitride‐based HFETs showed tremendous performance in both high‐power RF and power‐switching applications. AlGaN/GaN‐based high‐power HFETs on SiC substrate with 60‐nm gate lengths have achieved maximum oscillation frequency of 300 GHz. On‐resistance of 1.1–1.2 Ω mm as well as drain current of ∼0.9 A/mm was also achieved. For HFET devices operated in class AB mode on GaN semiinsulating substrates, a continuous‐wave power density of 9.4 W/mm was obtained with an associated gain of 11.6 dB and a power‐added efficiency of 40% at 10 GHz. III‐Nitride devices for power‐switching application have achieved near‐theoretical limit for vertical devices‐based GaN native substrates and breakdown voltage as high as 1200 V and on‐resistance as low as 9 mΩ‐cm 2 for lateral HFET devices on low‐cost silicon substrates. Because of the much larger 2DEG density in lattice‐matched InAlN/GaN HFETs, drain current as high as 2 A/mm was demonstrated, and the highest current gain cutoff frequency of 370 GHz was also reported on 7.5‐nm‐thick In 0.17 Al 0.83 N barrier HFETs. The very low on‐resistance allows high drain current, but it is subject to the junction temperature the devices can tolerate and is also restricted by the thermal expansion mismatch of the GaN‐on‐Si structures. Normally‐on and Normally‐off GaN HFETs with breakdown voltages in the range of 20–900 V are already commercially available. However, their competitivity against Si‐based IGBT and super junction MOSFETs and SiC‐FETs would depend on several factors such as voltage derating (used voltage versus the breakdown voltage), long‐term reliability, and cost. The advent of high‐quality SiGe layers on Si substrates has paved the way for the exploration and exploitation of heterostructure devices in an Si environment. MODFETs based on the Si/SiGe have been achieved with extraordinary p ‐channel performance. With 0.25‐μm gate lengths, the current gain cutoff frequency is about 40 GHz. When the gate length was reduced to 0.1 μm, the current gain cutoff frequency increased to about 70 GHz. MODFETs based on Ga 2 O 3 , especially β‐Ga 2 O 3 , have attracted a good deal of interests by the potential high breakdown voltage of Ga 2 O 3 but suffer from limitations imposed by both low electron mobility (affects efficiency and loss) and low thermal conductivity, hindering heat dissipation.