Title :
A comparative study of metal-semiconductor-metal photodetectors on GaAs with indium-tin-oxide and Ti/Au electrodes
Author :
Seo, Jong-Wook ; Ketterson, Andrew A. ; Ballegeer, Daniel G. ; Cheng, Keh-Yung ; Adesida, Ilesanmi ; Li, Xiaonan ; Gessert, Timothy
Author_Institution :
Dept. of Electr. & Comput. Eng., Illinois Univ., Urbana, IL, USA
Abstract :
Metal-semiconductor-metal (MSM) photodiodes with interdigitated indium-tin-oxide (ITO) electrodes have been fabricated on undoped GaAs using reactive-ion-etching in a methane plasma. The responsivity of ITO MSMs is measured to be approximately 0.8 A/W, which is twice that of conventional Ti/Au MSMs under normal operational bias conditions at lambda =850 nm. This higher responsivity is attributed to the transparency of the ITO electrodes. ITO MSMs exhibited a linear optical response over a wider bias range than Ti/Au MSMs. Also, a higher breakdown voltage was measured for ITO MSMs. The bandwidths of ITO and Ti/Au MSMs fabricated on the same semiconductor layer with 1- mu m fingers and spaces were measured to be 6 and 9 GHz, respectively. The slower response of the ITO MSMs is due to the longer transit time of the carriers generated beneath the ITO electrodes.<>
Keywords :
electrodes; integrated optics; integrated optoelectronics; metal-semiconductor-metal structures; optical workshop techniques; photodetectors; photodiodes; sputter etching; 6 GHz; 850 nm; 9 GHz; GaAs; IR; ITO electrodes; InSnO; MSM photodiodes; Ti-Au electrodes; bandwidths; bias range; breakdown voltage; linear optical response; metal-semiconductor-metal photodetectors; methane plasma; operational bias conditions; reactive-ion-etching; responsivity; transit time; transparency; Bandwidth; Electrodes; Fingers; Gallium arsenide; Gold; Indium tin oxide; Photodetectors; Photodiodes; Plasma measurements; Voltage measurement;
Journal_Title :
Photonics Technology Letters, IEEE
