Silicon carbide (SiC) wide bandgap semiconductor power device technologies offer improved electrical and thermal performance over silicon in high performance power electronic applications, such as hybrid or fully electric vehicles, aerospace, solar inverters, and advanced military systems. However, current packaging limitations make it difficult to operate these devices to their full potential. One such limitation includes die interconnections, which are traditionally made using large diameter aluminum wire bonds. This discussion introduces an innovative wire bondless interconnect technique for power packaging called PowerStep. This approach includes a precision etched metal tab with raised regions matching the size and location of device terminals and trenches to accommodate critical features on devices such as passivated surfaces. The tab offers a low profile, low inductance, low resistance, high electrical and thermal conductivity, and mechanically rugged interconnection solution. PowerStep has been implemented to facilitate a single-step interconnection method for a 600 to 1700 V SiC electronics package, replacing wire bonds which are connected one at a time. In addition, a key element of this package is the absence of a baseplate, resulting in lower weight, volume, and cost, as well as reduced manufacturing complexity. The electrical, thermal, and mechanical characteristics of PowerStep interconnections are analyzed and compared to conventional aluminum wire bonds to demonstrate the advantages of wire bondless interconnections coupled with wide bandgap devices. The low parasitics and junction-to-case thermal resistance of the package combined with PowerStep interconnects capture the high performance of SiC for power applications.
Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text X. Miao, B. Passmore, A. Gin, S. Vangala, W. Goodhue, E. Shaner, and I. Brener, "Doping-Tunable Metamaterials in the Mid-Infrared," in Frontiers in Optics 2009/Laser Science XXV/Fall 2009 OSA Optics & Photonics Technical Digest, OSA Technical Digest (CD) (Optica Publishing Group, 2009), paper PDPB8. Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article
We describe a time-domain spectroscopy system in the thermal infrared used for complete transmission and reflection characterization of metamaterials in amplitude and phase. The system uses a triple-output near-infrared ultrafast fiber laser, phase-locked difference frequency generation and phase-matched electro-optic sampling. We will present measurements of several metamaterials designs.
Voltage isolation inside power modules is paramount for functional and reliable operation. The dielectric potting materials are further stressed as the overall size of these modules is reduced due to size, weight, and cost considerations while the operating voltage of the modules continue to increase. Voltage ratings of silicon carbide device technologies will continue to increase above 6.5 kV into the tens of kilovolts in the future. Silicon carbide devices are also often operated at higher junction temperatures in order to take advantage of the high temperature capabilities of the material. As the module temperature increases, the dielectric strength of insulating materials in the module tend to decrease, which is a serious consideration for a compact power module operating at many kilovolts. A plurality of high temperature rated, high dielectric strength potting materials were tested for voltage breakdown and leakage current up to 30 kV and 250 °C. A range of different materials, both conventional and novel, were tested including silicones and parylene. Materials were selected with a dielectric strength greater than 500 V/mil, an operating temperature range of 200 °C or higher, and low hardness and modulus of elasticity with the intent of demonstrating the capability of blocking 20 kV or more in a reasonable thickness. A custom test setup was constructed to apply the voltage to test samples while measuring the breakdown voltage and simultaneous recording the leakage current. Test coupons were designed to provide a range of dielectric thicknesses over which to test the dielectric strength. Although voltage isolation may increase with increased dielectric thickness, the V/mil isolation rate often decreases. The performance degradation of these materials over temperature is plotted and deratings are suggested for use with medium voltages at operating temperatures above 175 °C.
Switch cells consist of an array of power switches and passive components which can replace the main switches in many power topologies, allowing reduced switching loss without altering the power topology directly. This paper discusses the development of a switch cell topology that utilizes a saturable resonant inductor to reduce the size and power loss of the cell. Additionally, the cell transfers energy stored in the inductor into a capacitor for efficient energy storage during the cell's conduction region. This energy is then transferred back to the system when the cell turns off, thus reducing the total switching energy.
For the first time, a new 900V, 10mOmega SiC MOSFET chip is fabricated, tested, and assembled in a >400A, half bridge power module, with only 1.25-2.5mOmega on-resistance at 25deg C, depending on the number of chips per switch position (i.e., eight or four, respectively). The SiC MOSFET chip had a measured breakdown > 1kV, and a specific RDS(ON) of 2.3mOmega cm2. The chips were then assembled in 16 power modules, and characterized up to 175deg C. Only a 40- 50% increase in RDS(ON) was measured with a temperature increase from 25deg C to 150deg C. With no knee voltage, conduction losses relative to comparably rated Si IGBT power modules can be reduced up to 70%.
We experimentally demonstrate that the resonance of a thermal-infrared metamaterial on a semiconductor substrate can be shifted by the substrate doping. We further study the electrical tuning of metamaterial resonance via finite integral time-domain simulation.
We demonstrate strong coupling between a surface plasmon and intersublevel transitions in self-assembled InAs quantum dots. The surface plasmon mode exists at the interface between the semiconductor emitter structure and a periodic array of holes perforating a metallic Pd/Ge/Au film that also serves as the top electrical contact for the emitters. Spectrally narrowed quantum-dot electroluminescence was observed for devices with varying subwavelength hole spacing. Devices designed for 9, 10, and 11 μm wavelength emission also exhibit a significant spectral splitting. The association of the splitting with quantum-dot Rabi oscillation is consistent with results from a calculation of spontaneous emission from an interacting plasmonic field and quantum-dot ensemble. The fact that this Rabi oscillation can be observed in an incoherently excited, highly inhomogeneously broadened system demonstrates the utility of intersublevel transitions in quantum dots for investigations of coherent transient and quantum coherence phenomena.
