Which mechanism causes increased light extraction in LEDs grown epitaxially upon sapphire crystals that meet the angle of total internal refraction?

💡 Explanation

When LEDs are fabricated using crystal substrates exceeding the critical angle, light extraction diminishes until Bragg scattering redirects photons to escape the crystal. Bragg diffraction operates; therefore scattering is increased rather than complete internal reflection occurring as expected in homogeneous film.

• Which risk increases when operating Stirling engine near Carnot limit?
• Which consequence results when repulsive forces dominate in antibonding orbitals?
• Which consequence results when the Carnot efficiency limit is reached during a refrigeration cycle?
• Which outcome results when a quantum mechanical wave function passes through a classically forbidden region of potential energy?
• Which risk increases when supercritical carbon dioxide power plant efficiency nears critical point during a cooling cycle?
• Which mechanism induces spontaneous emission when an electron transitions between orbitals?