Mev Ion Beam Induced Index of Refraction Changes in Layered GaAs/AlGaAs Waveguides
- PDF / 380,277 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 75 Downloads / 163 Views
ABSTRACT Previously, we showed that localized optical modifications could be produced without subsequent post thermal annealing in selectively masked planar GaAs/Al. 4Ga.6 As waveguide structures using 10 MeV oxygen ions. In our present investigation, irradiation experiments were performed on masked GaAs/Al.4 Ga.6As waveguide samples at 298 K using 10 MeV oxygen and 8 MeV carbon ions. The two ion incident energies were chosen to yield the maximum electronic stopping power near the interface separating the top cladding layer and the guiding layer. This localized modification process emphasizes the crucial role that the electronic energy transfer plays on the degree to which the refractive index of the guiding layer is altered. Propagation loss measurements on the fabricated channel waveguides were performed by end fire coupling a laser diode source at a wavelength of 1.3 lim. Observation of the extracted propagation loss values reveal that further optimization of the ion beam parameters are required before practical applications can be achieved. The relative efficiency
of the various ions to induce optically altered regions which serve as lateral confinement barriers of laser light shows that this fabrication process is sensitive to the ion beam current. INTRODUCTION Ion beam processing offers the advantage of being a highly controllable modification technique, in addition to being a cost effective alternative to some techniques which require time consuming processing steps. The technical approach centers around the ability of energetic ions to influence the bulk optical properties of planar waveguide materials [1]. The most conventional method by which to alter the optical properties of infrared semiconductor waveguides focuses on implanting chemically suitable ion species directly into the quantum layered structures. Most optical modifications techniques of this choice rely upon the potential of low energy (keV) ions to transfer energy to the target material through a high number of nuclear collisions [2-4]. These nuclear collisions, which are dominant during the end of the ion's projected range, can lead to a cascade of lattice site displacements. If the cascade distributions sufficiently overlap one another a number of bulk material properties can be modified. In a quantum layered semiconductor waveguide a high probability of target atom displacement sites are desirable near the interface separating two dissimilar layers. After 371 Mat. Res. Soc. Symp. Proc. Vol. 396 ©1996 Materials Research Society
displacement the lattice atoms can migrate and optimally relax back into site defects created during the collision interaction process. In order to achieve a high defect density a large ion fluence level is needed, in some cases as high as lxl016 ions/cm 2 [5]. Unfortunately, in many of these cases recoil collisions can lead to damage of the original lattice. Further device processing development is restricted by the need for a high temperature post bombardment annealing step. Furthermore, chemical effects that th
Data Loading...
