Light-emitting device with internal non-specular light redirection and anti-reflective exit surface

A method for making a semiconductor light-emitting device, the method comprising:

• forming within a semiconductor diode structure one or more light-emitting active layers that are arranged so as to emit an active-layer output light at a nominal vacuum wavelength λ0 to propagate within the semiconductor diode structure, the semiconductor diode structure being characterized with respect to an ambient medium by a critical angle ΘC at the nominal vacuum wavelength λ0;
• forming on a front surface of the semiconductor diode structure an anti-reflection coating that is arranged so that the front surface exhibits reflectivity that is less than corresponding Fresnel reflectivity of an interface between the ambient medium and a material of the front surface of the semiconductor diode structure without the anti-reflection coating, for light incident on the front surface within the semiconductor diode structure at an incidence angle less than ΘC at the nominal vacuum wavelength λ0, and with the front surface against the ambient medium;
• and
• forming on a back surface of the semiconductor diode structure a redirection layer, the redirection layer including one or more of (i) an array of nano-antennae, (ii) a partial photonic bandgap structure, (iii) a photonic crystal, or (iv) an array of meta-atoms or meta-molecules, the redirection layer being structurally arranged so as to redirect at least a portion of the active-layer output light, incident within the semiconductor diode structure on the redirection layer at an incidence angle greater than ΘC, to propagate toward the front surface of the semiconductor diode structure at an incidence angle with respect to the front surface that is less than ΘC,
• the semiconductor light-emitting device exhibiting (i) transmission by the front surface, as a device output light that propagates in the ambient medium, of first and second portions of the active-layer output light propagating within the semiconductor diode structure, the first portion without redirection by the redirection layer and the second portion with redirection by the redirection layer, and (ii) a mean number of redirections per photon emitted by the active layer, by the redirection layer before transmission by the front surface, that is less than 30.

A method for operating a semiconductor light-emitting device assembly, the method comprising supplying an electric power to the semiconductor light-emitting device so that the semiconductor light-emitting device emits a device output light from a front surface of a semiconductor diode structure to propagate in an ambient medium against the front surface:

• the front surface of the semiconductor diode structure being characterized, with respect to the ambient medium, by a critical angle ΘC at a nominal vacuum wavelength λ0;
• one or more light-emitting active layers within the semiconductor diode structure being arranged so as to emit an active-layer output light at the nominal vacuum wavelength λ0 to propagate within the semiconductor diode structure;
• an anti-reflection coating on the front surface of the semiconductor diode structure being arranged so that the front surface exhibits reflectivity that is less than corresponding Fresnel reflectivity of an interface between the ambient medium and a material of the front surface of the semiconductor diode structure without the anti-reflection coating, for light incident on the front surface within the semiconductor diode structure at an incidence angle less than ΘC at the nominal vacuum wavelength λ0, and with the front surface against the ambient medium;
• a redirection layer on a back surface of the semiconductor diode structure including one or more of (i) an array of nano-antennae, (ii) a partial photonic bandgap structure, (iii) a photonic crystal, or (iv) an array of meta-atoms or meta-molecules, the redirection layer being structurally arranged so as to redirect at least a portion of the active-layer output light, incident within the semiconductor diode structure on the redirection layer at an incidence angle greater than ΘC, to propagate toward the front surface of the semiconductor diode structure at an incidence angle with respect to the front surface that is less than ΘC,
• the semiconductor light-emitting device exhibiting (i) transmission by the front surface, as the device output light that propagates in the ambient medium, of first and second portions of the active-layer output light propagating within the semiconductor diode structure, the first portion without redirection by the redirection layer and the second portion with redirection by the redirection layer, and (ii) a mean number of redirections per photon emitted by the active layer, by the redirection layer before transmission by the front surface, that is less than 30.