Article comprising an epitaxial multilayer mirror

Abstract

Abstract We have found a way to, e.g., substantially increase the number of layers in a pseudomorphic strained layer semiconductor mirror over the number obtainable in an analogous conventional mirror, making it possible to obtain pseudomorphic strained layer mirrors of increased reflectance. Such a pseudomorphic mirror consists of alternating layers of a first and a second semiconductor material (e.g., Ge x Si 1-x /Si), of thickness t 1 and t 2 , and refractive index n 1 and n 2 , respectively, with the number of layer pairs chosen such that the mirror thickness is less than or equal to the "critical thickness" L c . For thicknesses >L c the mirror will contain dislocations. An article according to the invention comprises a mirror whose layer thicknesses are chosen such that n 1 t 1 ≠n 2 t 2 , with n 1 t 1 +n 2 t 2 =pλ/2, (p being an odd integer, typically 1). In other words, the optical thickness of the layers is not the conventional pλ/4. The thicknesses are also chosen such that the average lattice mismatch between substrate and mirror is reduced, compared to the analogous conventional (λ/4) mirror. Mirrors according to the invention can be advantageously used in optoelectronic devices such as surface emitting lasers and p-i-n photodetectors.

Inventors

• 👤 John C. Bean
• 👤 David L. Windt

Bibliographic Details