Band bending is a central concept in solid-state physics that arises from local variations in charge distribution especially near semiconductor interfaces and surfaces [1][2][3]. Its precision measurement is vital in a variety of contexts from the optimisation of field effect transistors [4][5][6] to the engineering of qubit devices with enhanced stability and coherence [7][8][9]. Existing methods are surface sensitive and are unable to probe band bending at depth from surface or bulk charges related to crystal defects [1, 10-12]. Here we propose an in-situ method for probing band bending in a semiconductor device by imaging an array of atomic-sized quantum sensing defects to report on the local electric field. We implement the concept using the nitrogen-vacancy centre in diamond [13,14], and map the electric field at different depths under various surface terminations. We then fabricate a two-terminal device based on the conductive two-dimensional hole gas formed at a hydrogen-terminated diamond surface [15], and observe an unexpected spatial modulation of the electric field attributed to a complex interplay between charge injection and photo-ionisation effects. Our method opens the way to three-dimensional mapping of band bending in diamond and other semiconductors hosting suitable quantum sensors, combined with simultaneous imaging of charge transport in complex operating devices [16].The emergence of semiconductor-based quantum sensing technologies in the last decade has opened new opportunities in a range of disciplines across physics, materials science and biology [17]. While most existing applications involve sensors that are external to the target sample to be measured [18,19], in-situ quantum sensors can also be an extremely valuable resource to study the sample itself by enabling three-dimensional (3D) mapping [20]. For semiconductor materials this is especially advantageous as it allows information to be gained on * These authors contributed equally to this work. †

The SiC/SiO 2 interface is a central component of many SiC electronic devices. Defects intrinsic to this interface can have a profound effect on their operation and reliability. It is therefore crucial to both understand the nature of these defects and develop characterization methods to enable optimized SiCbased devices. Here we make use of confocal microscopy to address single SiC/SiO 2-related defects and show the technique to be a noncontact, nondestructive, spatially resolved and rapid means of assessing thequality of the SiC/SiO 2 interface. This is achieved by a systematic investigation of the defect density of the SiC/SiO 2 interface by varying the parameters of a nitric oxide passivation anneal after oxidation. Standard capacitance-based characterization techniques are used to benchmark optical emission rates and densities of the optically active SiC/SiO 2-related defects. Further insight into the nature of these defects is provided by low-temperature optical measurements on single defects.

Au-hyperdoped Si absorbs near-infrared (NIR) light and recent efforts have successfully produced Si-based NIR photodetectors based on this property but with low detection efficiencies. Here, we investigate the differences between the optical and photocurrent properties of Au-hyperdoped Si. Although defects introduced during fabrication of these materials may not exhibit significant optical absorption, we show that they can produce a measurable photocurrent under NIR illumination. Our results indicate that the optimal efficiency of impurity-hyperdoped Si materials is yet to be achieved and we discuss these opportunities in light of our results. This work thus represents a step forward in demonstrating the viability of using impurity-hyperdoped Si materials for NIR photodetection.

Hyperdoped Si formed by implantation followed by pulsed laser melting is a promising material for enhanced near-infrared photodetection. To realize the full potential of this material, it is crucial to understand the nature of defects arising from the fabrication process and how these may impact device operation. Here, we identify through deep level transient spectroscopy the presence of a range of defects in the substrate depletion layer that arise from interactions between high dose ion implantation and pulsed laser melting, and investigate their annealing behavior up to 650°C. In particular, the detection of a vacancy complex E1(0.35) with densities as high as 1014cm−3 indicates that optical transitions between this level and the valence band may compete with the Au donor center, and hence could potentially contribute to the photocurrent in hyperdoped photodiodes.

Significant progress has been achieved with silicon carbide (SiC) high power electronics and quantum technologies, both drawing upon the unique properties of this material. In this Perspective, we briefly review some of the main defect characterization techniques that have enabled breakthroughs in these fields. We consider how key data have been collected, interpreted, and used to enhance the application of SiC. Although these fields largely rely on separate techniques, they have similar aims for the material quality and we identify ways in which the electronics and quantum technology fields can further interact for mutual benefit.

Color centers that emit light at telecommunication wavelengths are promising candidates for future quantum technologies. A pressing challenge for the broad use of these color centers is the typically low collection efficiency from bulk samples. Here, we demonstrate enhancements of the emission collection efficiency for Er3+ incorporated into 4H-SiC surface nano-pillars fabricated using a scalable top-down approach. Optimal Er ion implantation and annealing strategies are investigated in detail. The substitutional fraction of Er atoms in the SiC lattice is closely correlated with the peak photoluminescence intensity. This intensity is further enhanced via spatial wave-guiding once the surface is patterned with nano-pillars. These results have broad applicability for use with other color centers in SiC and also demonstrate a step toward a scalable protocol for fabricating photonic quantum devices with enhanced emission characteristics.

A giant, anomalous piezo-response of fully-depleted silicon-on-insulator (FD-SOI) devices under mechanical stress is demonstrated using impedance spectroscopy. This piezo-response strongly depends on the measurement frequency, ω, and consists of both a piezoresistance (PZR) and piezocapacitance whose maximum values are πR = −1100×10 −11 Pa −1 and πC = −900×10 −11 Pa −1 respectively. These values should be compared with the usual bulk PZR in p-type silicon, πR = 70 × 10 −11 Pa −1 . The observations are well described using models of space charge limited electron and hole currents in the presence of fast electronic traps having stress-dependent capture (ωc) and emission rates. Under steady-state conditions (i.e. when ω ωc) where the impedance spectroscopy measurements yield results that are directly comparable with previously published reports of PZR in depleted, silicon nano-objects, the overall piezo-response is just the usual, bulk silicon PZR. Anomalous PZR is observed only under non-steady-state conditions when ω ≈ ωc, with a symmetry suggesting that the electro-mechanically active fast traps are native Pb0 interface defects. The observations suggest new functionalities for FD-SOI, and shed light on the debate over the PZR of carrier depleted nano-silicon.

Defects introduced by low fluence arsenic, antimony, erbium, and bismuth ion implantation have been investigated as a function of annealing temperature using deep level transient spectroscopy (DLTS) and Laplace-DLTS. The defects produced by heavy ion implantation are stable up to higher temperatures than those introduced by electron irradiation and low mass ions. This result is attributed to the enhanced defect interactions that take place in the dense collision cascades created by heavy ion implantation. As a consequence, broadened DLTS features are apparent, especially after annealing. Using high energy resolution Laplace-DLTS, the well-known singly charged divacancy and vacancy-donor pair are accompanied by additional apparent defect signals. This shows that Laplace-DLTS is highly sensitive to the type of damage present, and extreme care must be exercised for reliable Arrhenius analysis.