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Field effect transistor

a field effect transistor and transistor technology, applied in the field of field effect transistors, can solve the problems of increased specific on-state resistance and circuit breakage, and achieve the effect of low specific on-state resistance and high work function

Inactive Publication Date: 2007-06-14
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009] In view of the foregoing technical problem, an object of the present invention is to provide a field effect transistor that achieves a normally-off o

Problems solved by technology

However, as a device for power control, normally off operation is demanded which interrupts current between the source and drain at a gate voltage of 0 V as in Si power MOS transistors.
When the normally-on type device is applied to the device of power control circuit, the circuit may be broken due to short-circuit.
However, in this case, there is a problem that the specific on-state resistance is increased.

Method used

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Experimental program
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embodiment 1

[0046]FIG. 1 is a sectional view showing a field effect transistor using a conductive oxide for a gate electrode according to Embodiment 1 of the present invention.

[0047] In FIG. 1, reference numeral 101 denotes a sapphire substrate, reference numeral 102 denotes an AlN buffer layer, reference numeral 103 denotes a first undoped GaN layer, reference numeral 104 denotes a first undoped AlGaN layer, reference numeral 105 denotes a SiO2 thin film, reference numeral 106 denotes a Ti / Al drain electrode, reference numeral 107 denotes a ZnInSnO gate electrode, and reference numeral 108 denotes a Ti / Al source electrode.

[0048]FIG. 1 shows the configuration of the field effect transistor of so-called normally-off type according to Embodiment 1. A threshold voltage VP is larger than 0 V. The feature of this configuration is the use of ZnInSnO for the gate electrode. In this configuration, the AlN buffer layer 102 having a thickness of 0.5 μm, the first undoped GaN layer 103 having a thicknes...

embodiment 2

[0059]FIG. 4 is a sectional view showing a field effect transistor using a conductive oxide for a gate electrode according to Embodiment 2 of the present invention.

[0060] In FIG. 4, reference numeral 401 denotes an n-type Si substrate, reference numeral 402 denotes an AlN buffer layer, reference numeral 403 denotes a first undoped GaN layer, reference numeral 404 denotes a first undoped AlGaN layer, reference numeral 405 denotes a Ti / Al drain electrode, reference numeral 406 denotes a ZnInSnO gate electrode, reference numeral 407 denotes a Ti / Al source electrode, reference numeral 408 denotes a Au wire, reference numeral 409 denotes a via hole, and reference numeral 410 denotes an Al backside source electrode.

[0061]FIG. 4 shows the configuration of the field effect transistor using the ZnInSnO gate electrode 406 according to Embodiment 2. In this configuration, the AlN buffer layer 402 having a thickness of 200 nm, the first undoped GaN layer 403 having a thickness of 1 μm, and th...

embodiment 3

[0066]FIG. 6 is a sectional view showing a field effect transistor using a conductive oxide for a gate electrode according to Embodiment 3 of the present invention.

[0067] In FIG. 6, reference numeral 601 denotes a GaN substrate, reference numeral 602 denotes a first undoped GaN layer, reference numeral 603 denotes a first undoped AlGaN layer, reference numeral 604 denotes a Ti / Al drain electrode, reference numeral 605 denotes an AlGaNOx oxide layer, reference numeral 606 denotes a ZnInSnO gate electrode, and reference numeral 607 denotes a Ti / Al source electrode.

[0068]FIG. 6 shows the structure of the field effect transistor using ZnInSnO for the gate electrode according to Embodiment 3. In this structure, the first undoped GaN layer 602 having a thickness of 5 μm and the first undoped AlGaN layer having a thickness of 12 nm and are formed in this order on a plane (0001) of the GaN substrate 601. In this epitaxial layer, the composition ratio of the first undoped AlGaN layer 603 i...

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Abstract

A material of a gate electrode is a conductive oxide having a higher work function than that of conventionally used Pd and so on, thereby achieving a normally-off transistor without reducing the sheet carrier concentration of a heterojunction. It is thus possible to achieve a normally-off operation while reducing an increase in the specific on-state resistance.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a field effect transistor using a nitride semiconductor, which is applicable to a power switching device for use in the power supply circuit of a consumer appliance. BACKGROUND OF THE INVENTION [0002] GaN semiconductor is promising for the material of future high power switching devices owing to its high saturation velocity and breakdown electric field. So far, AlGaN / GaN hetero-junction field effect transistor (HFETs) have been demonstrated with both a low specific on-state resistance and high breakdown voltage taking advantage of inherent high sheet carrier density at the hetro-interface caused by built-in polarization field. Further, as substrate materials, GaN wide-gap semiconductor materials can be grown on Si substrates that can be increased in area with a high thermal conductivity and low cost, as well as conventionally used sapphire and SiC substrates. Thus GaN semiconductor has a number of advantages to power dev...

Claims

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Application Information

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IPC IPC(8): H01L31/00
CPCH01L21/28581H01L29/2003H01L29/42316H01L29/475H01L29/7786H01L29/4175
Inventor MORITA, TATSUOUEDA, TETSUZO
Owner PANASONIC CORP
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