The complete characterization of a novel Direct Detection Device (DDD) camera for transmission electron microscopy is reported, for the first time at primary electron energies of 120 keV and 200 keV. Unlike a standard Charge Coupled Device (CCD) camera, this device does not require a scintillator. The DDD transfers signal up to 65 lines/mm providing the basis for a high-performance platform for a new generation of wide field-of-view high-resolution cameras. An image of a thin section of virus particles is presented to illustrate the substantially improved performance of this sensor over current indirectly coupled CCD cameras.

Cross-plane electronic and thermal transport properties of p-type La0.67Sr0.33MnO3/LaMnO3 perovskite oxide metal/semiconductor superlattices J. Appl. Phys. 112, 063714 (2012) Polarization Coulomb field scattering in In0.18Al0.82N/AlN/GaN heterostructure field-effect transistors J. Appl. Phys. 112, 054513 (2012) Modulation doping to control the high-density electron gas at a polar/non-polar oxide interface Appl. Phys. Lett. 101, 111604 (2012) Ultra low-resistance palladium silicide Ohmic contacts to lightly doped n-InGaAs ohmic contact structures rapid thermal annealed at 650, 750, 850, and 950°C have been analyzed using complementary transmission electron microscopy and electrical characterization techniques. The relationship between annealing temperature, interfacial microstructure, and contact resistance is examined. Annealing temperatures of 750°C or higher are required to produce an ohmic contact. Contacts annealed at 750 and 850°C show a planar interface between contact and the AlGaN layer, with minimal consumption of the AlGaN and the formation of a thin TiN interfacial layer. Annealing at 950°C produces the lowest contact resistance, with a structure showing inclusions through the AlGaN/GaN layer. These inclusions are also shown to be a Ti-nitride, having an Al/Au-rich metallurgical barrier layer surrounding them. However, this metallurgical layer does not produce an electrical barrier.

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We report the first use of direct detection for recording electron backscatter diffraction patterns. We demonstrate the following advantages of direct detection: the resolution in the patterns is such that higher order features are visible; patterns can be recorded at beam energies below those at which conventional detectors usefully operate; high precision in cross-correlation based pattern shift measurements needed for high resolution electron backscatter diffraction strain mapping can be obtained. We also show that the physics underlying direct detection is sufficiently well understood at low primary electron energies such that simulated patterns can be generated to verify our experimental data. DOI: 10.1103/PhysRevLett.111.065506 PACS numbers: 61.05.JÀ, 07.78.+s, 68.37.Hk Electron backscatter diffraction (EBSD) is a scanning electron microscope (SEM) based method in which diffraction of low-energy-loss electrons as they exit through the topmost few tens of nanometers leads to Kikuchi diffraction. In most EBSD studies the incident electron beam is stepped across a grid of points on the sample surface and the EBSD patterns analyzed in an automated way to determine crystal phase, orientation, or lattice strain variation. The EBSD method has evolved rapidly over the last two decades [1][2][3][4][5]. Most research has been directed to the application of this versatile tool to an ever increasing array of problems in materials characterization but the analysis methods themselves have also advanced, notably in three dimensional imaging using focused ion beam (FIB)-SEM [6-9] and in strain mapping [10][11][12][13][14]. However, the detector technology used to record EBSD patterns has essentially remained unchanged for over a decade and now limits performance in several application areas, such as strain resolution and low dose mapping, and prevents the development of new areas.The earliest EBSD patterns were recorded on film either exposed directly to the electrons in the chamber [15][16][17], or indirectly imaging a phosphor screen using a camera outside the vacuum [18]. Subsequently, these were replaced by various image intensified cameras giving the convenience of a live image of the pattern at the scintillator but with degraded pattern quality compared to that recorded using film [19]. Subsequently, scintillator coupled CCDs were introduced in the early 1990s [20,21]. In a limited number of examples tapered fiber-optic bundles have been used to couple the CCD to the scintillator with good results [20] but the alternative optical lens coupling has been adopted in the vast majority (> 95%) of instruments currently in use. Departures from these detection schemes have included an investigation of microchannel plates [22] and the adoption of a retarding electrostatic field for energy filtering [23].In other fields there have been significant advances in detectors directly exposed to the imaging beam for the detection of x rays [24,25] and medium energy electrons [26][27][28][29]. The current development of TEM instr...

Au Pd Al Ti ∕ Al Ga N ∕ Ga N ohmic contact structures with varying Ti:Al ratios have been investigated. The relationship between Ti:Al ratio, interfacial microstructure, and contact resistance is examined. Rapid thermal annealing temperatures of 850°C or higher are required to produce an ohmic contact with annealing at 950°C producing the lowest contact resistance in the majority of samples. Samples annealed at 950°C have been analyzed using complementary transmission electron microscopy and electrical characterization techniques. A thin Ti-nitride region is found to form at the contact/semiconductor interface in all samples. Ti-nitride inclusions through the AlGaN∕GaN layer are also observed, surrounded by an Al∕Au rich metallurgical barrier layer, with the size of the inclusions increasing with Ti content. The size of these inclusions does not have any clear effect on the electrical characteristics of the contacts at room temperature, but samples with fewer inclusions show superior electrical characteristics at high temperatures.