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TERAHERTZ OSCILLATOR AND METHOD FOR MANUFACTURING SAME

Foreign code F210010572
File No. (S2020-0159-N0)
Posted date 2021年11月1日
Country 世界知的所有権機関(WIPO)
International application number 2021JP000069
International publication number WO 2021171787
Date of international filing 令和3年1月5日(2021.1.5)
Date of international publication 令和3年9月2日(2021.9.2)
Priority data
  • 特願2020-030428 (2020.2.26) JP
Title TERAHERTZ OSCILLATOR AND METHOD FOR MANUFACTURING SAME
Abstract [Problem] To provide a terahertz oscillator and a method for manufacturing the same, the terahertz oscillator having no metal-insulator-metal (MIM) capacitor structure, which is cumbersome to make, and which oscillates by resonance of a resonant-tunneling diode (RTD) and a stabilizing resistor.
[Solution] A slot antenna is formed by providing a slot between a first electrode plate and a second electrode plate to which a bias voltage is applied, and a stabilizing resistor is disposed in the slot to connect the first electrode plate and the second electrode plate. An RTD is provided on the second electrode plate with a mesa therebetween, and an electrically conductive member is provided to form an air bridge between the first electrode plate and the mesa, the RTD and the stabilizing resistor resonating to produce oscillation.
Outline of related art and contending technology BACKGROUND ART
Although the hertz (THz) frequency band (approximately 0.1 THz~ 10 THz) located between radio waves and light waves is an undeveloped frequency band, various applications such as imaging and high-speed communication are anticipated in practical use. For this reason, it is essential to develop a small size hertz oscillator. As one of these elements, a hertz oscillator using a double barrier resonant tunnel diode (RTD) element with a semiconductor nanostructure has been studied. This hertz oscillator is currently the only electronic device capable of oscillating at 1~ 2 THz frequencies at room temperature alone. However, this hertz oscillator has a very small output of approximately 10μW, which leads to a problem in that it is complicated and complex to manufacture.
Fig. 1 illustrates a conventional hertz oscillator in which a lower electrode 4 is layered on an upper portion of a InP substrate 3 having a square shape of approximately 1 mm, and a slot antenna 2 including a recessed portion having an elongated shape (10~ 20 μm) is disposed in a substantially central portion of the lower electrode 4. Further, an upper electrode 5 and a stabilizing resistor (resistance value RS) 6 are disposed on the InP substrate 3, and a resonant tunnel diode (RTD) 1 having negative V (voltage)-I (current) characteristics as illustrated in Fig. 3 is disposed at a tip portion of the upper electrode 5 via a MIM (Metal Insulator Metal) capacitor 7. The stabilizing resistor 6 is connected between the lower electrode 4 and the upper electrode 5 in order to stabilize the oscillation operation, and the stabilizing resistor 6 is formed of, for example, an InGaAs sheet. The upper electrode 5 is grounded, and a DC bias (bias voltage Vb) is applied to the lower electrode 4. In the resonance tunnel diode (RTD) 1, when a bias voltage Vb is applied at a DC bias, electrons tunnel through the quantum level in the well, and a tunnel current flows, and when the bias voltage Vb is further applied, When the quantum level in the well is below the bottom of the conduction band of the emitter, electrons cannot tunnel and the current decreases, so V-I characteristics such as those illustrated in Fig. 3 are obtained. Electromagnetic waves can be oscillated and amplified by using the differential negative resistance characteristic "-GRTD" in which current decreases. Also, the resonant tunnel diode (RTD) 1 has a parasitic capacitance CRTD in parallel with the differential negative resistor "-GRTD", and radiates in a direction perpendicular to the standing wave of the electric field, as illustrated in Fig. 2. The output is determined by the radiation resistance of the slot antenna 2.
In this way, the conventional hertz oscillator has a resonant structure of RTD1 and MIM7, and the slot antenna 2 is formed by the MIM capacitance CMIM of the MIM7 and the RTD1. Since the slot antenna 2 is represented by a resonant circuit of LC and a radiation loss of Gant, the equivalent circuit of this oscillator is a circuit such as that illustrated in Fig. 4. The oscillation start condition is when the positive value GRTD of the differential negative resistance characteristic becomes equal to or greater than the radiation loss Gant as indicated by Equation 1 below, and oscillates at the frequency fOSC indicated by Equation 2 below.
Further, an equivalent circuit of an oscillator including a bias circuit (bias voltage Vb) is as illustrated in Fig. 5, and a MIM capacitance CMIM of a MIM capacitor 7 and a resistance value RS of a stabilizing resistor 6 are connected in parallel; The inductance LS of the slot antenna 2 exists between RTD1 and MIM capacitance CMIM, and the inductance LW of the line exists between the bias circuit and the resistance value RS. A circulating current i such as that illustrated in Fig. 1 flows around the slot antenna 2, and an inductance LS is formed due to the circulating current i. Also, in the equivalent circuit of Fig. 5, the MIM capacitance CMIM shorts and the inductance LW is released at high frequencies, so as to form a resonant circuit of RTD1 and inductance LS, as illustrated in Fig. 6 (A). Further, at low frequencies, the inductances LS and LW are ignored, and the resistance value RS cancels the NDR (negative differential resistance value) of RTD1. thus, as illustrated in Fig. 6 (B), a resonant circuit is formed of RTD1, the bias voltage Vb, and the resistance value RS of the stabilizing resistor 6.
  • Applicant
  • ※All designated countries except for US in the data before July 2012
  • TOKYO INSTITUTE OF TECHNOLOGY
  • Inventor
  • SUZUKI Safumi
  • MAI Van Ta
  • SUZUKI Yusei
  • ASADA Masahiro
IPC(International Patent Classification)
Specified countries National States: AE AG AL AM AO AT AU AZ BA BB BG BH BN BR BW BY BZ CA CH CL CN CO CR CU CZ DE DJ DK DM DO DZ EC EE EG ES FI GB GD GE GH GM GT HN HR HU ID IL IN IR IS IT JO JP KE KG KH KN KP KR KW KZ LA LC LK LR LS LU LY MA MD ME MG MK MN MW MX MY MZ NA NG NI NO NZ OM PA PE PG PH PL PT QA RO RS RU RW SA SC SD SE SG SK SL ST SV SY TH TJ TM TN TR TT TZ UA UG US UZ VC VN WS ZA ZM ZW
ARIPO: BW GH GM KE LR LS MW MZ NA RW SD SL SZ TZ UG ZM ZW
EAPO: AM AZ BY KG KZ RU TJ TM
EPO: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
OAPI: BF BJ CF CG CI CM GA GN GQ GW KM ML MR NE SN ST TD TG
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