Recent developments in monolithic integration of InGaAsP/InP optoelectronic devices

Monolithically integrated optoelectronic circuits combine optical devices such as light sources (injection lasers and light emitting diodes) and optical detectors with solid-state semiconductor devices such as field effect transistors, bipolar transistors, and others on a single semiconductor crystal. Here we review some of the integrated circuits that have been realized and discuss the laser structures suited for integration with emphasis on the InGaAsP/InP material system. Some results of high frequency modulation and performance of integrated devices are discussed

Brief Announcement: Space Bounds for Reliable Multi-Writer Data Store:Inherent Cost of Read/Write Primitives

LNCS v. 9363 entitled: Distributed Computing: 29th International Symposium, DISC 2015, Tokyo, Japan, October 7-9, 2015, ProceedingsBack Matter pp. 647-678We consider a complete graph of n nodes, any pair of which can communicate with each other directly through one of F available wireless channels. n is not known to the nodes. Time is divided into synchronous rounds. In each round, a node can select at most one channel to listen to or transmit on. Transmission is successful if there is exactly one node transmitting on a channel (and one or more nodes listening). If two or more nodes transmit on the same channel, a collision occurs and their transmissions fail. Nodes can detect collisions, i.e., can distinguish collision from silence. We study distributed solutions to the information exchange problem: given initially k nodes each holding a packet, the task is to disseminate these k packets to all n nodes as quickly as possible. We assume that multiple packets can be packed in a single message. Recently, due to the advent of mobile devices that can operate on multiple channels, some attention has been given to studying the effect of multiple channels on improving communication [1–4]. However, all existing works require prior knowledge of n. In ad hoc networks, to make n known to all the nodes in fact can be a tough task. Moreover, in ad hoc networks, the value of n could change sporadically or even frequently due to nodes leaving and joining. Hence, there is practical need for designing uniform protocols that do not require any prior information about the network including n and k. Not knowing the parameters n or k greatly increases the difficulty of designing fast algorithms, especially in the case where different nodes can operate on different channels, as it is hard to manage the transmission probabilities over the distributed set of nodes

Deep level defects in n-type GaN grown by molecular beam epitaxy

Deep-level transient spectroscopy has been used to characterize electronic defects in n-type GaN grown by reactive molecular-beam epitaxy. Five deep-level electronic defects were observed, with activation energiesE1=0.234±0.006, E2=0.578±0.006, E3=0.657±0.031, E4=0.961±0.026, and E5=0.240±0.012 eV. Among these, the levels labeled E1, E2, and E3are interpreted as corresponding to deep levels previously reported in n-GaN grown by both hydride vapor-phase epitaxy and metal organic chemical vapor deposition. Levels E4 and E5do not correspond to any previously reported defect levels, and are characterized for the first time in our studies

Metal oxide-graphene field-effect transistor: interface trap density extraction model

A simple to implement model is presented to extract interface trap density of graphene field effect transistors. The presence of interface trap states detrimentally affects the device drain current-gate voltage relationship Ids-Vgs. At the moment, there is no analytical method available to extract the interface trap distribution of metal-oxide-graphene field effect transistor (MOGFET) devices. The model presented here extracts the interface trap distribution of MOGFET devices making use of available experimental capacitance-gate voltage Ctot-Vgs data and a basic set of equations used to define the device physics of MOGFET devices. The model was used to extract the interface trap distribution of 2 experimental devices. Device parameters calculated using the extracted interface trap distribution from the model, including surface potential, interface trap charge and interface trap capacitance compared very well with their respective experimental counterparts. The model enables accurate calculation of the surface potential affected by trap charge. Other models ignore the effect of trap charge and only calculate the ideal surface potential. Such ideal surface potential when used in a surface potential based drain current model will result in an inaccurate prediction of the drain current. Accurate calculation of surface potential that can later be used in drain current model is highlighted as a major advantage of the model

Implication of the overlap representation for modelling generalized parton distributions

Based on a field theoretically inspired model of light-cone wave functions, we derive valence-like generalized parton distributions and their double distributions from the wave function overlap in the parton number conserved s-channel. The parton number changing contributions in the t-channel are restored from duality. In our construction constraints of positivity and polynomiality are simultaneously satisfied and it also implies a model dependent relation between generalized parton distributions and transverse momentum dependent parton distribution functions. The model predicts that the t-behavior of resulting hadronic amplitudes depends on the Bjorken variable x_Bj. We also propose an improved ansatz for double distributions that embeds this property.Comment: 15 pages, 8 eps figure

Observation of white-light amplified spontaneous emission from carbon nanodots under laser excitation

Author name used in this publication: Li Bin TangAuthor name used in this publication: Siu Fung YuAuthor name used in this publication: Shu Ping LauVersion of RecordPublishe

High-power, single-mode operation of an InGaAsP/InP laser with a grooved transverse junction using gain stabilization

The high-power performance of a groove InGaAsP/InP transverse junction laser fabricated on a semi-insulating InP substrate has been investigated. Peak power of over 250 mW/facet for pulsed operation and 11 mW/facet cw are achieved with stable fundamental mode operation and narrow beam width. It is suggested that the single-mode operation is caused by a gain stabilizing mechanism related to the transverse junction injection profiles