@article{mullen_boulton_pan_kim_2024, title={Electronic properties of c-BN/diamond heterostructures for high-frequency high-power applications}, volume={143}, ISSN={["1879-0062"]}, DOI={10.1016/j.diamond.2024.110920}, abstractNote={Using first principles calculations, this work investigates the suitability of diamond/c-BN heterojunctions for high frequency, high power device applications. The key quantities of band offsets and interface charge polarization are examined for different crystallographic orientations [(110), (111), or (100)], bond terminations (CB or CN), and substrates (diamond or c-BN). The results indicate that both the (111) and (100) structures with polar interfaces are likely to be a type-I alignment with the diamond conduction and valence band extrema nested within the c-BN bandgap, whereas the non-polar (110) counterpart may form type II as the valence band of c-BN is shifted down substantially lower. The valence band offsets are estimated to be around 0.2–0.55 eV and 1.2–1.3 eV for types I and II, respectively, with only a modest dependence on the order of layer stacking and bond termination. The (111) and (100) structures also show net charge polarization in a narrow region at the interface. The electron-deficient and electron-rich nature of the CB and CN bonding are found to induce charge redistribution leading to an essentially 2D sheet of negative and positive polarization, respectively, with a density on the order of 1012−1013q/cm2 (q=1.6×10−19 C). With the predicted band alignments suitable for carrier confinement as well as the possibility of the modulation and polarization doping, the diamond/c-BN heterostructures are a promising candidate for high-performance electronic devices with a highly conductive 2D channel. Both p-type and n-type devices appear possible with a judicious choice of the heterojunction configuration.}, journal={DIAMOND AND RELATED MATERIALS}, author={Mullen, Jeffrey T. and Boulton, James A. and Pan, Minghao and Kim, Ki Wook}, year={2024}, month={Mar} }
 @article{el-sherif_briggs_bersch_pan_hamidinejad_rajabpour_filleter_kim_robinson_bassim_2021, title={Scalable Characterization of 2D Gallium-Intercalated Epitaxial Graphene}, volume={13}, ISSN={["1944-8252"]}, DOI={10.1021/acsami.1c14091}, abstractNote={Scalable synthesis of two-dimensional gallium (2D-Ga) covered by graphene layers was recently realized through confinement heteroepitaxy using silicon carbide substrates. However, the thickness, uniformity, and area coverage of the 2D-Ga heterostructures have not previously been studied with high-spatial resolution techniques. In this work, we resolve and measure the 2D-Ga heterostructure thicknesses using scanning electron microscopy (SEM). Utilizing multiple correlative methods, we find that SEM image contrast is directly related to the presence of uniform bilayer Ga at the interface and a variation of the number of graphene layers. We also investigate the origin of SEM contrast using both experimental measurements and theoretical calculations of the surface potentials. We find that a carbon buffer layer is detached due to the gallium intercalation, which increases the surface potential as an indication of the 2D-Ga presence. We then scale up the heterostructure characterization over a few-square millimeter area by segmenting SEM images, each acquired with nanometer-scale in-plane resolution. This work leverages the spectroscopic imaging capabilities of SEM that allows high-spatial resolution imaging for tracking intercalants, identifying relative surface potentials, determining the number of 2D layers, and further characterizing scalability and uniformity of low-dimensional materials.}, number={46}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={El-Sherif, Hesham and Briggs, Natalie and Bersch, Brian and Pan, Minghao and Hamidinejad, Mahdi and Rajabpour, Siavash and Filleter, Tobin and Kim, Ki Wook and Robinson, Joshua and Bassim, Nabil D.}, year={2021}, month={Nov}, pages={55428–55439} }