Ž . Journal of Non-Crystalline Solids 227–230 1998 1118–1122 a-Si:Hra-SiC:H waveguides and modulators for low-cost silicon-integrated optoelectronics G. Cocorullo a,c , F.G. della Corte a, ) , R. de Rosa b , I. Rendina a , A. Rubino b , E. Terzini b a IRECE - Consiglio Nazionale delle Ricerche, Via Diocleziano, 328 I-80124 Naples, Italy b ENEA - Centro Ricerche Portici, Via Vecchio Macello, I-80055 Portici, Naples, Italy c DEIS - UniÕersity of Calabria, I-87036 Rende, Cosenza, Italy Abstract Starting from an a-Si:Hra-SiC:H stack deposited by glow discharge on a crystal silicon wafer, we have fabricated and measured the properties of rib waveguides suitable for infrared optical communication purposes. Propagation losses as small as 0.7 dBrcm have been measured. The same waveguiding structure has been utilised for the construction of Fabry–Perot interferometers. As the process is compatible with the standard microelectronic technologies, the integration of optical and electronic functions on the same chip becomes possible. q 1998 Elsevier Science B.V. All rights reserved. 1. Introduction Many efforts are devoted today to the study of new optical materials compatible with the technol- ogy of silicon, which is by far the most important wx material for electronics 1 . In the large class of materials produced by the plasma enhanced chemical Ž . vapour deposition PECVD , there are several candi- dates for integrated optolelectronics, and hydro- Ž . genated amorphous silicon a-Si:H is certainly one of the most interesting. So far, the most important application of a-Si:H as optoelectronic material was in photovoltaic applications. Recently, however, new chances for a-Si:H as a material suitable for opto- electronics were pointed out: light-emitting diodes w x wx 2,3 and infrared detectors 4 have been produced ) Corresponding author. Tel.: q39 81 5707999; fax: q39 81 5705734; e-mail: dellacor@irecel.irece.na.cnr.it. operating at the infrared wavelengths of 1.3 and 1.5 m m, the conventional II and III windows of fiber optic communication systems, opening the way to the integration of optoelectronic tasks on a silicon chip. The main advantage of a-Si:H is its deposition temperature that decreases the production costs and makes it compatible with the very large scale inte- Ž . gration VLSI technology. Another important bene- fit is that its optical gap can be changed. In fact, by mixing the main process gas, i.e., SiH , with other 4 components such as CH , CO or NO during the 4 2 2 plasma discharge, it is possible to obtain alloys with a wider gap, while the opposite change is achieved by adding GeH . 4 In this paper, for the first time, we present a three-dimensional rib waveguide defined by pho- tolithography out of a stacked structure of the type a-Si:Hra-SiC:H, grown by PECVD on a silicon wafer. The stepwise refractive index structure pro- 0022-3093r98r$19.00 q 1998 Elsevier Science B.V. All rights reserved. Ž . PII: S0022-3093 98 00290-7