Optically-biased, edge-coupled InP/InGaAs heterojunction phototransistors

InP photodetectors for millimeter-wave applications

“…The first experimental demonstration of InP heterojunction phototransistor able to operate in the millimeter wave frequency range is, to our knowledge, due to David Wake 12 with a two terminal HPT with no base contact. More recent experimental and theoretical results confirmed the capabilities of InP HPT for millimeter wave applications, either vertical 13 or edge illuminated 14 .…”

A new phototransistor with uni-travelling-carrier and optically gradual coupling properties

“…The layer structure is as follows, InP buffer, 0.5−μm thick, Si−doped at 1×10 19 3 . Here, the conventional thin space layer between the emitter and base was not used to lessen the outdiffusion of a base dopant [5], because we want to use the outdiffusion of a base dopant into the emitter to form a thin p−type emitter, which can effi− ciently lower the dark current [15]. The device was formed by dry−etching into the subcollector about 0.2−μm depth to obtain the ridge of 3−μm width, and then 0.4−μm thick SiO 2 layer was deposited by PECVD to passivate the ridge, followed by forming a contact window on the top of the ridge through photolithography.…”

“…Among them, the edge−coupled two−terminal HPT (ECTT− HPT) had been proved by Wake et al to have high gain and high frequency response [5] due to its efficient small area and low parasitics. Based on the edge−coupled and two−ter− minal structure, Ng et al added InGaAlAs to the ECTT− HPT as a waveguide to obtain improvement in optical power handling and coupling efficiency [20].…”

“…The HPT's large inter− nal gain [3][4][5] and compatibility with heterojunction bipolar transistor (HBT) in epitaxial layer and process provide the possibility of fabrication of high performance and cost−ef− fective optoelectronic integrated circuits (OEICs) [6][7][8][9]. In the widely researched radio−over−fiber (ROF) system, the HPT based on InP material systems is regarded as one promising solution to the very simple base station because it can perform photodetection and frequency mixing simulta− neously [10][11][12][13].…”

“…The HPT has been studied for more than two decades [14], many types of it have been developed for high perfor− mances, such as two−terminal, three−terminal, surface−nor− mal−coupled, edge−coupled, single heterojunction, double heterojunction, and travelling−wave types [4,5,[16][17][18][19][20][21][22]. Among them, the edge−coupled two−terminal HPT (ECTT− HPT) had been proved by Wake et al to have high gain and high frequency response [5] due to its efficient small area and low parasitics.…”