Thermally conductive coatings for light emitting devices

Abstract

A light emitting device, such as semiconductor laser diodes, superluminescent devices, semiconductor amplifiers and polymer-based light emitting devices, is provided with a coating that will increase the thermal conductivity at one or more facets of the device to provide for lowering the facet temperature during device operation to suppress the occurrence of temperature dependent facet degrading mechanisms and the catastrophic optical damage (COD) level of the light emitting device since these facet attributes are directly affected by temperature at the facet. In the preferred embodiment, the coating should have a thermal conductivity that is higher than the material of the light emitting device. The high thermal conductivity coating provides for an efficient transfer of heat away from the beam emission area of the front facet into regions adjacent to, i.e., above or below the active region of the device, such as layers of the device underlying the active region and the device substrate. If the coating material does not provide a sufficiently high level of thermal conductivity, then thermal resistance should be taken into consideration and the coating should be made thicker to achieve lower thermal resistance and, therefore, higher heat spreading toward lowering the facet temperature. In either case, the rate of heat transfer from the facet is enhanced so that the onset of higher temperature dependent facet degrading mechanisms and COD developing at the device facet are reduced or suppressed.