Effects of hydrostatic and uniaxial stress on the Schottky barrier heights of Ga-polarity and N-polarity n-GaN

Liu, Y.; Kauser, M. Z.; Nathan, M. I.; Ruden, P. P.; Doğan, S.; Morkoç̌, H.; Park, S. S.; Lee, K. Y.

doi:10.1063/1.1689392

Cited by 48 publications

(25 citation statements)

References 16 publications

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“…It has been reported that the SBHs of GaAs, 30,31 GaN, 32 and GaAlN 33 Schottky barrier shift under stress and strain due to the band structure change and piezoelectric effect. Experiments and calculations have shown that the band gap changes under strain and stress.…”

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confidence: 99%

Flexible Piezotronic Strain Sensor

et al. 2008

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Strain sensors based on individual ZnO piezoelectric fine-wires (PFWs; nanowires, microwires) have been fabricated by a simple, reliable, and cost-effective technique. The electromechanical sensor device consists of a single electrically connected PFW that is placed on the outer surface of a flexible polystyrene (PS) substrate and bonded at its two ends. The entire device is fully packaged by a polydimethylsiloxane (PDMS) thin layer. The PFW has Schottky contacts at its two ends but with distinctly different barrier heights. The I-V characteristic is highly sensitive to strain mainly due to the change in Schottky barrier height (SBH), which scales linear with strain. The change in SBH is suggested owing to the strain induced band structure change and piezoelectric effect. The experimental data can be well-described by the thermionic emission-diffusion model. A gauge factor of as high as 1250 has been demonstrated, which is 25% higher than the best gauge factor demonstrated for carbon nanotubes. The strain sensor developed here has applications in strain and stress measurements in cell biology, biomedical sciences, MEMS devices, structure monitoring, and more.

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confidence: 99%

Flexible Piezotronic Strain Sensor

et al. 2008

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“…By assuming S, A ** , T, and N D are to be known, φ s can, in principle, be derived from the ln I-V plot. 12 Subsequently, the strain-induced change in SBH can be determine by 12,17,18 …”

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confidence: 99%

“…Since the stress dependence of A ** arises only from the stress dependence of the effective mass, the first term is much smaller than the second term and is thus neglected in the following discussion. 17,18,23 The change of SBH ∆φ s with strain for bias of 1.0 V is plotted in Figure 3c (black curve). Similarly, under a bias of -1.0 V, the change of SBH ∆φ d with strain is calculated and the data are plotted in Figure 3c (red curve).…”

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confidence: 99%

Piezoelectric-Potential-Controlled Polarity-Reversible Schottky Diodes and Switches of ZnO Wires

et al. 2008

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Using a two-end bonded ZnO piezoelectric-fine-wire (PFW) (nanowire, microwire) on a flexible polymer substrate, the strain-induced change in I-V transport characteristic from symmetric to diode-type has been observed. This phenomenon is attributed to the asymmetric change in Schottky-barrier heights at both source and drain electrodes as caused by the strain-induced piezoelectric potential-drop along the PFW, which have been quantified using the thermionic emission-diffusion theory. A new piezotronic switch device with an "on" and "off" ratio of ∼120 has been demonstrated. This work demonstrates a novel approach for fabricating diodes and switches that rely on a strain governed piezoelectric-semiconductor coupling process.Binary switching is the principle of many electronic devices for applications such as data storage and logic circuits. Up to now most of the nanoscale switches are operated by an electrostatic force between a suspended carbon nanotube (CNTs)/nanowire and its counter electrode to switch between "on" and "off" depending on mechanical contact. [1][2][3] As the size of the devices reaching nanoscale, a small gap of ∼10 nm is required to be maintained between the CNTs/nanowire and the electrode for electro-mechanical switching. In such a case, the van der Waals interaction between the CNT and the electrode may be strong enough to bind the two together so that the device cannot perform the "off" function as required. Furthermore, the random thermal vibration at the tip of CNT may also become sufficiently large at conventional operating temperatures, which can strongly increase the device instability. 4 As a result, the reliability, lifetime and manufacturability of these devices are challenged.The Schottky barrier diode, a metal-semiconductor (MS) rectifying junction that generally exhibits switching effect, may overcome the drawbacks. ZnO, a material that exhibits semiconductor and piezoelectric properties, is likely a candidate for fabricating diode-based switching devices.Recently, various novel devices have been fabricated using ZnO nanowires/nanobelts by utilizing its coupled piezoelectric and semiconducting properties (piezotronic effect), such as nanogenerators, 5,6 piezoelectric field effect transistors and chemical sensors, 7,8 piezoelectric diodes, 9 triggers, 10 transducer and actuator, 11 and flexible piezotronic strain sensors. 12 In this letter, we report a new type flexible piezotronic switch device that is built using a single ZnO piezoelectric fine wire (PFW) (nanowire, microwire). Its operation mechanism relies on the piezoelectric potential induced asymmetric change in Schottky-barrier height (SBH) at the source and drain electrodes. The change of SBH is caused by the combined effects from strain-induced band structure change and piezoelectric potential. The device demonstrated here presents a new electromechanical switch built based on piezotronic effect. 13 For this study, the device was fabricated by bonding an ultralong ZnO PFW laterally on a polystyrene (PS) substrate,...

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“…Previously, an increase of the Schottky barrier height of GaN with pressure was observed and attributed to a combination of piezoelectric and band structure effects [1]. Similarly, the increase in the ex- trapolated barrier height of the AlGaN MSM structure with pressure is tentatively attributed to that same mechanism.…”

Section: Resultsmentioning

confidence: 91%

“…Recent work by Liu et al reported on the effects of hydrostatic and uniaxial stress on the electrical characteristics of Schottky diodes on n-type GaN [1]. In the present work, we demonstrate the effect of hydrostatic pressure on the current vs. voltage characteristics of Al x Ga 1-x N metal-semiconductor-metal (MSM) structures.…”

Section: Introductionmentioning

confidence: 75%

AlGaN metal‐semiconductor‐metal structure for pressure sensing applications

Hassan

Lee

et al. 2006

Phys. Status Solidi (c)

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We report on the effects of hydrostatic pressure on an Al x Ga 1-x N metal-semiconductor-metal (MSM) structure with Ni Schottky contacts. Structural, optical, and electrical analysis of the Al x Ga 1-x N film were carried out using atomic force microscopy (AFM), high resolution X-ray diffraction (HRXRD), Raman, UV-visible spectroscopy, and Hall effect measurements. The AlN mole fraction in this film was determined to be about 24%. Current-voltage (I-V) measurements of the MSM structure under hydrostatic pressure indicated a linear decrease of current with pressure. The decrease of the current under pressure was attributed to an increase in barrier height, tentatively attributed to a combination of piezoelectric and band structure effects.

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Effects of hydrostatic and uniaxial stress on the Schottky barrier heights of Ga-polarity and N-polarity n-GaN

Cited by 48 publications

References 16 publications

Flexible Piezotronic Strain Sensor

Flexible Piezotronic Strain Sensor

Piezoelectric-Potential-Controlled Polarity-Reversible Schottky Diodes and Switches of ZnO Wires

AlGaN metal‐semiconductor‐metal structure for pressure sensing applications

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