GaN-based heterostructures for sensor applications

Stutzmann, M.; Steinhoff, G.; Eickhoff, Martin; Ambacher, O.; Nebel, Christoph E.; Schalwig, J.; Neuberger, R.; Müller, Gerhard

doi:10.1016/s0925-9635(02)00026-2

Cited by 160 publications

(87 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…36,37 The 0.5-1 µm thick films were nominally N-polar and intrinsically n-type (~5×10 19 cm -3 ), with electron mobility's of approximately 400 cm 2 /V.s and an experimentally determined room temperature optical gap of 0.77 eV. 37 ARPES measurements were performed at ARPES beamline 10.0.1 and at the Microscopic …”

Section: Methodsmentioning

confidence: 99%

How Indium Nitride Senses Water

et al. 2017

View full text Add to dashboard Cite

The unique electronic band structure of indium nitride InN, part of the industrially significant III–N class of semiconductors, offers charge transport properties with great application potential due to its robust n-type conductivity. Here, we explore the water sensing mechanism of InN thin films. Using angle-resolved photoemission spectroscopy, core level spectroscopy, and theory, we derive the charge carrier density and electrical potential of a two-dimensional electron gas, 2DEG, at the InN surface and monitor its electronic properties upon in situ modulation of adsorbed water. An electric dipole layer formed by water molecules raises the surface potential and accumulates charge in the 2DEG, enhancing surface conductivity. Our intuitive model provides a novel route toward understanding the water sensing mechanism in InN and, more generally, for understanding sensing material systems beyond InN.

show abstract

Section: Methodsmentioning

confidence: 99%

How Indium Nitride Senses Water

et al. 2017

View full text Add to dashboard Cite

show abstract

“…The pH response of GaN surfaces using ISFET structures was recently reported by Steinhoff et al 8 However, no work on the pH response to AlGaN surfaces was done, and mechanism of pH response is not understood yet. Although Stutzmann et al 9 and Mehandru et al 10 reported preliminary results on the response of open-gate AlGaN / GaN HEMTs to polar liquids, the sensing properties of such devices have not systematically been investigated so far.…”

Section: Introductionmentioning

confidence: 99%

Liquid-phase sensors using open-gate AlGaN∕GaN high electron mobility transistor structure

Kokawa

Sato

Hasegawa

et al. 2006

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

View full text Add to dashboard Cite

Liquid-phase sensing characteristics of open-gate AlGaN / GaN high electron mobility transistor ͑HEMT͒ structures were investigated in aqueous solutions and polar liquids. In de-ionized water, the open-gate HEMT clearly showed good drain I-V characteristics with current saturation and pinch-off behavior, very similar to I-V characteristics of typical Schottky-gate HEMTs. We observed a fine parallel shift in the transfer curves according to change in the pH value in a solution, indicating the corresponding potential change at the AlGaN surface. The sensitivity for the potential change was 57.5 mV/ pH, very close to the theoretical value of 58.9 mV/ pH at 24°C for the Nernstian response to H + ions. In the low drain bias region, the drain current linearly decreased with the pH value. This also indicated a systematic potential change at the AlGaN surface due to pH change. The present open-gate device showed a fast response to the pH change and a stable operation at fixed pH values. A possible mechanism for the pH response of the AlGaN surface is discussed in terms of equilibrium reactions of hydroxyls at the AlGaN surface with H + in a solution. It was also found that the device was quite sensitive to changes in the electrostatic boundary conditions of the open-gate area by exposure to polar liquids. The drain current linearly decreased with increasing normalized liquid dipole moment.

show abstract

“…High electron mobility transistors (HEMT) based on the GaN/AlGaN heterostructure are very promising candidates as chemical and biological sensors since its sheet carrier density is strongly inuenced by the surface potential [1]. Furthermore, an opportunity of integration with solar blind UV detectors or high temperature, high power electronics makes GaN-based HEMT structures to be used for a variety of applications [2].…”

Section: Introductionmentioning

confidence: 99%

Electrostatic Gates for GaN/AlGaN Quantum Point Contacts

et al. 2012

View full text Add to dashboard Cite

We report on AlGaN/GaN quantum point contacts fabricated by using e-beam lithography and dry ion etching. The tunable nano-constrictions are dened by the integration of side and top gates in a single device. In this conguration, the planar gates are located on the both sides of a quantum channel and the metallic top gates, which cover the active region, are separated from the substrate by an insulating and passivating layers of HfO2 or Al2O3/HfO2 composite. The properties of devices have been tested at T = 4.2 K. For side gates we have obtained a very small surface leakage current Ig < 10 −11 A at gate voltages |Vg| < 2 V, however, it is not enough to close the quantum channel. With top gates we have been able to reach the pinch-o voltage at Vg = −3.5 V at a cost of Ig ≈ 10 −6 A, which has been identied as a bulk leakage current.

show abstract

GaN-based heterostructures for sensor applications

Cited by 160 publications

References 18 publications

How Indium Nitride Senses Water

How Indium Nitride Senses Water

Liquid-phase sensors using open-gate AlGaN∕GaN high electron mobility transistor structure

Electrostatic Gates for GaN/AlGaN Quantum Point Contacts

Contact Info

Product

Resources

About