We analyze the effects that the Ge profile shape has upon the bias and temperature characteristics of SiGe HBT's. The widely used bandgap reference (BGR) design equation and a more general analytical expression we developed incorporating Ge grading are used to compare silicon devices to their SiGe counterparts. Measurement and simulation show that although the Ge-ramp effect is negligible in th...

Memory based on phase change materials is currently the most promising candidate for bridging the gap in access time between memory and storage in traditional memory hierarchy. However, multilevel storage is still hindered by the so-called resistance drift commonly related to structural relaxation of the amorphous phase. Here, we present the temporal evolution of infrared spectra measured on am...

Highly photosensitive nanocrystal (NC) skins based on exciton funneling are proposed and demonstrated using a graded bandgap profile across which no external bias is applied in operation for light-sensing. Four types of gradient NC skin devices (GNS) made of NC monolayers of distinct sizes with photovoltage readout are fabricated and comparatively studied. In all structures, polyelectrolyte pol...

GeSn alloys with Sn contents of 8.4 % and 10.7 % are grown pseudomorphically on Ge buffers on Si (001) substrates. The alloys as-grown are compressively strained, and therefore indirect bandgap. Undercut GeSn on Ge microdisk structures are fabricated and strained by silicon nitride stressor layers, which leads to tensile strain in the alloys, and direct bandgap photoluminescence in the 3-5 µm g...

Identifying strong and fast nonlinearities for today’s photonic applications is an ongoing effort1. Materials2–5 and devices6–9 are typically sought to achieve increasing nonlinear interactions. We report large enhancement of two-photon absorption through intrinsic resonances using extremely non-degenerate photon pairs. We experimentally demonstrate two-photon absorption enhancements by factors...

We propose one-dimensional photonic bandgap (PB) dielectric structures to be used at grazing incidence in order to obtain an extended bandgap exhibiting considerably reduced reflection loss and dispersion compared to similar structures used at a normal incidence of light. The well-known quarter-wave condition is applied for the design in this specific case, resulting in resonance-free reflectio...

The inaccuracy of the analyses commonly used for predicting the temperature behavior of the IcV~ characteristics of transistors and the output of bandgap reference sources is pointed out. The problem is traced to a basic assumption implicit, in such analyses, namely that the variation of the bandgap voltage of silicon with temperature is Iinear; this assumption is shown to be of poor accuracy. ...

In contrast to the numerous reports on narrow-bandgap heterojunctions on silicon, such as strained Si1 xGex on silicon, there have been very few accounts of wide-bandgap semiconducting heterojunctions on silicon. Here, we present a wide-bandgap heterojunction—between titanium oxide and crystalline silicon—where the titanium oxide is deposited via a metal-organic chemical vapor deposition proces...

This paper presents a new structure of a bandgap circuit which can be programmed to get any desired output voltage. Unlike conventional bandgap circuits, the proposed bandgap circuit uses MOS transistors operating in subthreshold region instead of bipolar transistors to generate PTAT and IPTAT currents. Use of the current conveyor makes the circuit capable of being operated at lower supply volt...

Van der Waals heterostructures formed by assembling different two-dimensional atomic crystals into stacks can lead to many new phenomena and device functionalities. In particular, graphene/boron-nitride heterostructures have emerged as a very promising system for band engineering of graphene. However, the intrinsic value and origin of the bandgap in such heterostructures remain unresolved. Here...