Presentation on theme: "BENNY SHEINMAN, DAN RITTER MICROELECTRONIC RESEARCH CENTER"— Presentation transcript:
1 Monolithically Coupled Photo Diode - HBT or a Photo - HBT : A Modeled Comparison BENNY SHEINMAN, DAN RITTERMICROELECTRONIC RESEARCH CENTERELECTRICAL ENGINEERING DEPARTMENTTECHNION – ISRAEL INSTITUTE OF TECHNOLOGY
2 Workshop outline Introduction. Phototransistor electrical configurations.General bandwidth / efficiency limitations in a photo-detector.Additional limitation in a top illuminated PIN diode / phototransistor.Electrical modeling of the top illuminated PIN diode / phototransistor.
10 Cascode Configuration Performance comparableto that of a PIN + HBT?
11 Current Density [KA/cm Current Density [KA/cm Kirk effect50100150200250Current Density [KA/cm2]Frequency [GHz]650nm CollectorFtmax50100150200250300Current Density [KA/cm2]Frequency [GHz]150nm CollectorFmaxt
12 Kirk effect (cont.) Associated time constant for a 1*10 emitter and a 10 diameter optical window:
13 Photodetectors bandwidth limitations Carrier transit time:RC of detector capacitance and amplifier input resistance:M. Agethen et al. IPRM 2002
29 Model of top illuminated detector Solution of current equations is difficult:- distributed photocurrentPhotodiode capacitance / areaYet for a known capacitance value,a single pole fit gives good results480.2pF
33 ConclusionsIn the cascode configuration, photo-HBT have comparable performance to PIN detector + HBT processed from the same layers.PIN detector + HBT processed from different layers will have superior performance.The highly resistive base layer produces an internal filter in the top illuminated PIN detector.The influence of the filter should be included in the model of the detector.