title: Planar, Al0.3Ga0.7As-passivated-base, heterojunction bipolar phototransistors.
abstract: New planar GaAs heterojunction bipolar phototransistors have been designed and demonstrated. The devices use a GaAs/Al(0.3)Ga(0.7) As molecular-beam-epitaxy materials system with an Al(0.3)Ga(0.7) As passivated, 10-nm-thick base; a depleted, high-low emitter; and a low emitter-base capacitance. Electrical contact to the emitter is made by a set of parallel, ohmic fingers and to the collector by an ohmic contact formed in a large, approximately 1.48-microm deep via. Rise times in response to impulse optical excitation at 810 nm were 747-891 ps except at the two lowest optical excitation powers measured. Photocurrent gains measured at 810 and 850 nm were 0.67-19, depending on experimental conditions. These devices are promising for use in heterodyne photodetector arrays for coherent optical processing channelizers requiring a 100-MHz bandwidth.
authors.affiliation: Naval Research Laboratory, Washington, DC 20375-5347, USA.
authors.forename: G W
authors.initials: GW
authors.lastname: Anderson
authors.forename: F J
authors.initials: FJ
authors.lastname: Kub
authors.forename: T F
authors.initials: TF
authors.lastname: Carruthers
authors.forename: N A
authors.initials: NA
authors.lastname: Papanicolaou
authors.forename: M Y
authors.initials: MY
authors.lastname: Frankel
authors.forename: D S
authors.initials: DS
authors.lastname: Katzer
authors.forename: J A
authors.initials: JA
authors.lastname: Modolo
authors.forename: W F
authors.initials: WF
authors.lastname: Tseng