Photoluminescence excitation spectroscopy is a contactless characterization technique that can provide valuable information about the surface and bulk recombination parameters of a semiconductor device, distinct from other sorts of photoluminescent measurements. For this technique, a temperature-tuned light emitting diode (LED) has several advantages over other light sources. The large radiation density offered by LEDs from near-infrared to ultraviolet region at a low cost enables efficient and fast photoluminescence measurements. A simple and inexpensive LED-based setup facilitates measurement of surface recombination velocity and bulk Shockley-Read-Hall lifetime, which are key parameters to assess device performance. Under the right conditions, this technique can also provide a contactless way to measure the external quantum efficiency of a solar cell.

This paper describes a study of triple-zone junction termination extension (JTE) as an edge termination for 10 kV power devices on 4H-SiC. Blocking voltage is obtained from twodimensional numerical simulations using the MEDICI TM program, and is defined as the voltage where the ionization integral equals 0.9998 using impact ionization coefficients of Konstantinov, et al. Simulations are performed for triple-zone JTE on a 100 µm thick n-type epilayers doped 8x10 14 cm -3 . Each JTE zone is 100 µm wide. Blocking voltage is determined as a function of JTE dose for various values of the doping ratio α, defined as the ratio of the dose of ring (i) to the dose of ring (i+1), where i = 1 for the inner ring, 2 for the next ring, and so on. Best results are obtained for constant α (i.e. α 1 = α 2 = α). For this epilayer, the optimum α is 1.3, i.e. this α maintains a blocking voltage greater than 10 kV over the widest range of JTE doses. The depth of the JTE has little effect on blocking voltage for depths less than 2 µm.

An increasing number of density maps of macromolecular structures, including proteins and protein and DNA/RNA complexes, have been determined by cryo-electron microscopy (cryo-EM). Although lately maps at a near-atomic resolution are routinely reported, there are still substantial fractions of maps determined at intermediate or low resolutions, where extracting structure information is not trivial. Here, we report a new computational method, Emap2sec+, which identifies DNA or RNA as well as the secondary structures of proteins in cryo-EM maps of 5 to 10 Angstrom resolution. Emap2sec+ employs the deep Residual convolutional neural network. Emap2sec+ assigns structural labels with associated probabilities at each voxel in a cryo-EM map, which will help structure modeling in an EM map. Emap2sec+ showed stable and high assignment accuracy for nucleotides in low resolution maps and improved performance for protein secondary structure assignments than its earlier version when tested on simulated and experimental maps.

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We have designed, simulated, fabricated, and characterized high-voltage 4H-SiC p-channel DMOS-IGBTs on 20 kV blocking layers for use as the next generation of power switching devices. These p-IGBTs exhibit significant conductivity modulation in the drift layer. The maximum currents of the experimental p-channel IGBTs are 1.2x and 2.1x higher than the ideal 20 kV n-channel DMOSFETs at room temperature and 175°C, respectively.