Analysis of GaN MagHEMTs

Abstract

The simulations, calibration, measured output currents and relative sensitivity of the first-ever fabricated gallium nitride (GaN) magnetic high electron mobility transistors (MagHEMTs) are given in this work. The current imbalance and relative sensitivities obtained from simulations are calibrated against the experimental data measured at room temperature (RT). The average calculated relative sensitivity of the 60 fabricated devices measured is 11.98%T −1 . We present three-dimensional simulation results of GaN split-current magnetic sensors for different geometrical and biasing parameters at various ambient temperatures. The detailed analysis of device behaviour is given for each scenario. The relative sensitivity degrades at 400 K (S r =6.78%T −1 ) and 500K (S r =4.91%T −1 ) compared to the sensitivity measured at 300 K (S r =11.98%T −1 ). The GaN MagHEMTs show promising predicted relative sensitivities at 400 K and 500 K compared to silicon magnetic field effect transistors (MagFETs) operating at much lower temperatures. Moreover, device geometrical parameters are optimised to enhance the relative sensitivity from 11.98%T −1 to 23.29%T −1 using the commercial simulation toolbox Atlas, by Silvaco.

A physics-based electrical model of a magnetically sensitive AlGaN/GaN HEMT

“…The main drawback of the silicon MagFETs is their low magnetic sensitivity Sr (< 5 %T -1 ) originated mainly due to the modest electron mobility µe (< 600 cm 2 V -1 sec -1 ) in the inversion channel [4][5]. Besides the passive resistive sensors that rely on inhomogeneous narrow-gap semiconductors with high magnetoresistance [6], the emerging wide band-gap AlGaN/GaN hetero-junction technology has enabled the development of new class of the active magnetic sensors based on High-Electron Mobility Transistors (HEMTs) namely GaN MagHEMTs [7]- [10]. Owning to extremely high mobility µe (> 2000 cm 2 V -1 sec -1 ) of the electrons in 2-Dimensional Electron Gas (2DEG) channel [11], the first experimental GaN MagHEMTs have already exhibited a much higher sensitivity Sr (>17%) at room temperature [7][8][9][10] compared to their silicon counterparts.…”

Development of GaN Transducer and On-Chip Concentrator for Galvanic Current Sensing

“…The long and narrow silicon MagFETs and GaN MagHEMTs have demonstrated improved sensitivities [11], [17], [23] as the optimum length to width ratio (L/W) enhances the geometrical correction factor (GH) holding a linear Figure 3. Measured mean current imbalance (∆I) and its ratio to total current (I=ID1+ID2) in dual-drain GaN MagHEMTs at room temperature with device length of L=65 µm, device width of W=20 µm and gate to source spacing of LGS=7 µm for different gate length of LG=1 µm (squares), LG=2 µm (circles), LG=3 µm (triangles), LG=4 µm (diamonds) and LG=5 µm (stars) at VDS=0.5V and B=30 mT.…”

“…relationship with sensitivity [23]. In sensitivity calculations, the correction factor term takes into account the field distribution that is influenced by the non-ideality of sense contacts [17].…”

Coil Design for Integration with GaN Hall-Effect Sensors

“…Nevertheless, the study of spatial dependence of a magnetic sensor exposed area with or without a material field concentrator for various shapes and geometries of the coil is a difficult, tedious, and slow task. Such a task requires training and access to expensive electromagnetic field solver software such as ANSYS Maxwell/HFSS [10], SIMULIA CST [11], or TCAD [12] for integration analysis at chip level or various time-consuming restrictive spaces experiments on PCB level components.…”