A critical comparison of high-speed VCSEL characterization techniques

This paper critically compares, for the first time, common microwave and optical procedures used for the highspeed characterization of vertical-cavity surface-emitting lasers (VCSELs). The intrinsic small-signal modulation characteristics of a VCSEL are measured, and the related rate equation parameters are extracted. Observed trends show excellent agreement with theory. The modulation characteristics of the VCSEL are determined by examining three different responses: relative intensity noise, S21 response, and high-resolution optical spectra. The various experimental techniques yielded consistent results. The relative strengths and weaknesses of each measurement are investigated

Top emitting OLEDs with multi-layered mirror consisting of metallic and dielectric layers

We report on an investigation into the design and optimization of multi-layered mirror structures for top-emitting Organic Light Emitting Diodes (OLED). Our results show that the six-layer top mirror structure with optimally designed dielectric-enhanced metallic capping mirror proposed here exhibits more than three-fold improvement in the device luminance over the conventional LiF/Al top mirror The optical and electrical simulations were performed on a set of microcavity OLEDs consisting of widely used organic materials, N,N'-di(naphthalene-1-yl)-N,N'-diphenylbenzidine (NPB) as a hole transport layer and tris (8-hydroxyquinoline) (Alq(3)) as emitting and electron transporting layer. Ag was used as the anode/bottom mirror for maximum reflection. In order to optimize both the injection characteristics of the cathode and the cavity effect the structure of the multilayer top mirror was optimized, the structure used was a combination of a thin LiF/Al cathode capped by metallic and dielectric layers. The electroluminescence emission spectra, electric field distribution inside the device, carrier density, recombination rate and exciton density were calculated for devices with different top mirror configurations

Monitoring the electrical properties of the back silicon interface of silicon-on-sapphire wafers

The density and the electrical nature of the interface traps at the silicon-sapphire interface of silicon-on-sapphire (SOS) MOSFETs have a significant influence on the electrical characteristics of these transistors. This letter describes a simple MOS test structure for evaluating the electrical properties of this interface of SOS wafers. Measurement and modeling of the C-V characteristics of the test structure fabricated on production SOS wafers are presented. We have demonstrated that the C-V characteristics are an efficient tool for studying the depletion of the silicon-sapphire interface by the interface trapped charge