III-V Nitride based piezoresistive microcantilever for sensing applications

Abstract

III-V Nitride based microcantilevers, with AlGaN/GaN heterostructure field effect transistor as the piezoresistive deflection transducer, have been investigated under steady state, transient, ac, and UV illuminated conditions and compared to theoretical calculations. The steady state transverse gauge factor (GFt) was found to be much larger than theoretical estimates and increased regularly with more negative gate bias. Transient GFt demonstrated opposite sign but similar gate bias dependence and was measured as high as ∼860. Measurements under ac biasing conditions and UV illumination resulted in a lower GFt of ∼13, which agrees with theoretical calculations owing to elimination of charge trapping effects.

Unique detection of organic vapors below their auto-ignition temperature using III–V Nitride based triangular microcantilever heater

“…With commercial availability of high quality III-Nitride heterojunction epilayers on Si, the fabrication of these heaters is also quite straightforward. Although, III-Nitride based microcantilevers have been demonstrated earlier [11,25,26], there is no report so far on triangular microcantilever heaters and their sensing applications.…”

“…Microcantilevers offer excellent avenues for molecular sensing that arises out of their high sensitivity to various physical parameter changes induced by the analyte molecules [8][9][10][11][12][13][14][15]. Microcantilever heaters, which are extremely sensitive to changes in thermal parameters [16][17][18][19][20][21], have been widely utilized for calorimetry [16], thermal nanotopography [17] and thermal conductivity measurements [18].…”

High frequency dynamic bending response of piezoresistive GaN microcantilevers

“…The effect of mechanical strain, on 2DEG density and output characteristics of AlGaN/GaN heterostructure field effect transistors (HFETs), has been reported earlier. [8][9][10][11][12][13][14][15] High gauge factors (>100) have been reported for quasi-static and step bending response, 8,[12][13][14][15] however, the factors contributing to such high values, especially their deviation from much lower theoretical estimates, are poorly understood. Recently, very high gauge factor of À850 was reported for microcantilevers in transient condition, however, the corresponding dynamic response was not studied.…”

“…7 AlGaN/GaN heterostructures offer unique advantage over existing piezoresistive or piezoelectric materials, as it actually converts the piezoelectric response of these materials to piezoresistive response, since the two dimensional electron gas (2DEG) formed at the AlGaN/GaN interface gets modulated by the stress induced change in piezoelectric polarization. 8 The epitaxial growth of III-V nitride layers on a Si substrate enables direct integration of nitride microelectromechanical systems (MEMS) with mature Si based integrated circuits to develop miniaturized sensor systems.…”

Study of interface reactions between Ti/Al/Ni/Au metallization and AlGaN/GaN heterostructures

“…AlGaN/GaN heterostructure based sensors and field-effect transistors have been an area of intense interest for high temperature, high power, and high frequency electronic device applications [1][2][3][4].…”