Wide-Field Magnetic Field and Temperature Imaging Using Nanoscale Quantum Sensors

Abstract

The simultaneous imaging of magnetic fields and temperature (MT) is important in a range of applications, including studies of carrier transport 1-3 , solid-state material dynamics 1-6 , and semiconductor device characterization 7,8 . Techniques exist for separately measuring temperature (e.g., infrared (IR) microscopy 9 , micro-Raman spectroscopy 9 , and thermo-reflectance microscopy 9 ) and magnetic fields (e.g., scanning probe magnetic force microscopy 10 and superconducting quantum interference devices 11 ). However, these techniques cannot measure magnetic fields and temperature simultaneously. Here, we use the exceptional temperature 12,13 and magnetic field 14,15 sensitivity of nitrogen vacancy (NV) spins in conformally-coated nanodiamonds to realize simultaneous wide-field MT imaging. Our "quantum conformally-attached thermo-magnetic" (Q-CAT) imaging enables (i) wide-field, high-frame-rate imaging (100 -1000 Hz); (ii) high sensitivity; and (iii) compatibility with standard microscopes. We apply this technique to study the industrially important problem 8,16-18 of characterizing multifinger gallium nitride high-electron-mobility transistors (GaN HEMTs). We spatially and temporally resolve the electric current distribution and resulting temperature rise, elucidating functional device behavior at the microscopic level. The general applicability of Q-CAT imaging serves as an important tool for understanding complex MT phenomena in material science, device physics, and related fields.The NV center in diamond has attracted great interest because of its exceptional spin properties at room temperature, which exhibit outstanding nanoscale sensitivity to magnetic fields 14,19-23 and temperature 12,13 . NV centers located within nanodiamonds (NVNDs) have gained particular interest for applications including drug delivery 24 , thermal measurements of biological systems [25][26][27][28][29] , and scanning magnetometer tips 30,31 . The NVND's small size allows direct measurement of their local MT environment. These applications have motivated studies of NVND properties such as strain, magnetic and thermal sensitivity, and coherence time 32,33 . However, NVND properties differ for a given fabrication process 32 or surface treatment 34 . This variability of nanodiamond material parameters and orientations has presented challenges for wide-field imaging studies using NVNDs. In this work, we (i) develop a model that describes the optically detected magnetic resonance (ODMR) 35,36 spectrum of NVND ensembles as a function of magnetic field and temperature; (ii) perform statistical characterization of NVND parameters, specifically the variation in NVND thermal response with implications for NVND temperature sensing; (iii) use this NVND model and our statistical characterization to extend the capabilities of NV sensing by enabling wide-field imaging with deposited coatings of NVNDs (Q-CAT imaging); (iv) demonstrate our technique's capabilities by imaging the dynamic phenomenon of electromigration; and (v) perform wide-field MT...

Real-time nanodiamond thermometry probing in vivo thermogenic responses

“…For example, the present analysis shows +0.7°C at 23 min for the vehicle control in Fig. 4D, although its interpretation is not straightforward (46). Without determining dD/dT for each measured ND in situ (48), a quantitative interpretation of the temperature response curve would be challenging.…”

“…The possible variation of dD / dT can further affect the temperature values. While this study uses dD / dT = −65.4 kHz · °C −1 , as mentioned above, a dD / dT range of −50 to −100 kHz · °C −1 has been reported ( 46 ). Without determining dD / dT for each measured ND in situ ( 48 ), a quantitative interpretation of the temperature response curve would be challenging.…”

“…A value of −74 kHz · °C −1 was previously determined for the NV centers in bulk diamonds, with a sample variation from −71 to −84 kHz · °C −1 ( 43 – 45 ). It is known that dD / dT has greater inhomogeneity in NDs because of crystal strains and surface states ( 46 , 47 ), and it may be further affected in different types of ND samples. The calibration difficulty may also be a cause of the discrepancy.…”

Real-time nanodiamond thermometry probing in vivo thermogenic responses

“…For example, the present analysis shows +0.7°C at 23 min for the vehicle control in Fig. 4D, although its interpretation is not straightforward range of −50 to −100 kHz • °C −1 has been reported (46). Without determining dD/dT for each measured ND in situ (48), a quantitative interpretation of the temperature response curve would be challenging.…”

“…A value of −74 kHz • °C −1 was previously determined for the NV centers in bulk diamonds, with a sample variation from −71 to −84 kHz • °C −1 (43)(44)(45). It is known that dD/dT has greater inhomogeneity in NDs because of crystal strains and surface states (46,47), and it may be further affected in different types of ND samples. The calibration difficulty may also be a cause of the discrepancy.…”