Strain-sensing cryogenic field-effect transistor for integrated strain detection in GaAs/AlGaAs microelectromechanical systems

Beck, R. G.; Eriksson, Mats; Westervelt, R. M.; Campman, K. L.; Gossard, A. C.

doi:10.1063/1.115999

Cited by 39 publications

(22 citation statements)

References 11 publications

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“…͓DOI: 10.1063/1.1516237͔ Thin, suspended two-dimensional electron gas ͑2DEG͒ heterostructures have been recently perfected, and have subsequently been employed for nanoscale conducting devices. 1,2 In this letter, we present a high-resolution displacement readout that is based upon our ability to achieve very high mobility suspended quantum wires. Molecular beam epitaxial ͑MBE͒ grown materials are directly patterned and in-plane gates are used to excite the vibration.…”

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confidence: 99%

Two-dimensional electron-gas actuation and transduction for GaAs nanoelectromechanical systems

Tang

Huang

Roukes

et al. 2002

Applied Physics Letters

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We have fabricated doubly clamped beams from GaAs/AlGaAs quantum-well heterostructures containing a high-mobility two-dimensional electron gas ͑2DEG͒. Applying an rf drive to in-plane side gates excites the beam's mechanical resonance through a dipole-dipole mechanism. Sensitive high-frequency displacement transduction is achieved by measuring the ac emf developed across the 2DEG in the presence of a constant dc sense current. The high mobility of the incorporated 2DEG provides low-noise, low-power, and high-gain electromechanical displacement sensing through combined piezoelectric and piezoresistive mechanisms. © 2002 American Institute of Physics. ͓DOI: 10.1063/1.1516237͔ Thin, suspended two-dimensional electron gas ͑2DEG͒ heterostructures have been recently perfected, and have subsequently been employed for nanoscale conducting devices. 1,2 In this letter, we present a high-resolution displacement readout that is based upon our ability to achieve very high mobility suspended quantum wires. Molecular beam epitaxial ͑MBE͒ grown materials are directly patterned and in-plane gates are used to excite the vibration. No metallization is needed, hence high Q values can be obtained.The starting material was a specially designed, MBEgrown, 2DEG heterostructure similar to that used in Ref. 1. The structural layer stack comprises seven individual layers having a total thickness of 115 nm. The top and bottom are thin GaAs cap layers preventing oxidation of the Al 0.3 Ga 0.7 As:Si donor layers in between. The central 10-nmthick GaAs layer forms a quantum well sustaining a high mobility 2DEG located 37 nm below the top surface and surrounded by two AlGaAs spacer layers. Below the structural layer stack is a 400 nm Al 0.8 Ga 0.2 As sacrificial layer. The structure was intentionally made asymmetric to avoid neutralizing the piezoelectric effect of GaAs.After ohmic contacts were deposited, a thick layer of poly-methyl-methacrylate ͑PMMA͒ is spun on the chip, followed by a single electron-beam lithography step to expose trenches in PMMA that isolate the beam from its side gates. PMMA was then employed as a direct mask against a low voltage electron cyclotron reactor etch performed to further etch the trenches to the sacrificial layer. After stripping off the PMMA, final structure relief is achieved by removing the sacrificial layer beneath the beams with diluted HF. To minimize the damage to the 2DEG from dry etching, a Cl 2 /He plasma was chosen because of its excellent etching characteristics, such as smooth surface morphology and vertical sidewall. A stable etching speed at 35Å /s is obtained under conditions of less than 150 V self-bias ͑20 W constant rf power͒, Cl 2 and He flow rate ratio 1:9, 3 mTorr pressure, and 300 W microwave power. With the same method, we have also fabricated suspended Hall bars and extensively characterized the resulting suspended 2DEG. Before processing, the initial mobility and density after illumination are 5.1 ϫ10 5 cm 2 /Vs, 1.26ϫ10 12 cm Ϫ2 , respectively. With our improved low damage etching...

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confidence: 99%

Two-dimensional electron-gas actuation and transduction for GaAs nanoelectromechanical systems

Tang

Huang

Roukes

et al. 2002

Applied Physics Letters

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“…Figure 4 shows the measured small signal response v DS of the FET for V GS = −15 mV and I D = 1.8 µA about the mechanical resonance of the chip. The voltage response is due mainly to the piezoelectric effect which couples stress in the FET substrate to a change in electronic sheet density in the channel [10]. Deflection was measured independently by a Michelson interferometer to obtain a volume strain in the region of the FET of ε = 8 × 10 −8 .…”

Section: Resultsmentioning

confidence: 99%

“…This paper is intended as a supplement to previous work describing the sensor at T ∼ 10 K [10]. At 77 K our FETs display a transconductance of 30 µS, a small signal drain-source resistance of 30 M , a white noise level corresponding to a gate charge noise q n < 0.7e Hz −1/2 where e is the charge of a single electron and a 1/ f noise corner of approximately 1 kHz.…”

Section: Introductionmentioning

confidence: 97%

Low noise field-effect transistor for integrated strain sensing in microelectromechanical systems at 77 K

Beck

Eriksson

Westervelt

et al. 1996

Superlattices and Microstructures

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“…[5][6][7] Recently, strain sensors have been demonstrated comprised of field-effect transistors ͑FETs͒ fabricated from a GaAs/AlGaAs heterostructure containing a twodimensional electron gas ͑2DEG͒. 8,9 Such strain sensors can be used in heterostructure SPM cantilevers and also have broader potential applications for detecting forces and displacements in GaAs/AlGaAs microelectromechanical systems ͑MEMS͒. 10,11 In this letter we describe the fabrication and operation of GaAs/Al 0.3 Ga 0.7 As SPM cantilevers with integrated strainsensing FETs.…”

mentioning

confidence: 99%

GaAs/AlGaAs self-sensing cantilevers for low temperature scanning probe microscopy

Beck

Eriksson

Topinka

et al. 1998

Applied Physics Letters

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Strain-sensing cryogenic field-effect transistor for integrated strain detection in GaAs/AlGaAs microelectromechanical systems

Cited by 39 publications

References 11 publications

Two-dimensional electron-gas actuation and transduction for GaAs nanoelectromechanical systems

Two-dimensional electron-gas actuation and transduction for GaAs nanoelectromechanical systems

Low noise field-effect transistor for integrated strain sensing in microelectromechanical systems at 77 K

GaAs/AlGaAs self-sensing cantilevers for low temperature scanning probe microscopy

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