LED Chip Passivation for Low Current Efficiency
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Solution Overview
Problem
Light-emitting diode chips based on InGaAlP have efficiency maxima at high current densities due to non-radiative losses on etched side surfaces, limiting their use at low current densities.
Innovation Solution
A passivation layer with statically fixed charge carriers is applied to the side surfaces of the semiconductor layer sequence, particularly covering the active zone, to reduce non-radiative recombination by shielding oppositely charged carriers, thereby increasing efficiency at low current densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If light-emitting diode chips based on InGaAlP are used, then efficiency maximum is achieved at high current densities, but non-radiative losses occur at etched side surfaces limiting use at low current densities
Solution Approach 1:
A passivation layer is introduced as an intermediary between the semiconductor material and the external environment. This passivation layer contains statically fixed charge carriers that create an electric field to shield mobile charge carriers from the etched side surfaces, thereby reducing non-radiative recombination losses while maintaining radiative efficiency in the active zone
Solution Approach 2:
The patent modifies the electrical parameters at the side surfaces by introducing statically fixed charge carriers in the passivation layer. This creates a localized electric field that changes the distribution of mobile charge carriers, preventing them from reaching the harmful etched surfaces and thereby changing the recombination characteristics from non-radiative to radiative
2Loss of energy
If passivation layer with statically fixed charge carriers is applied to side surfaces, then non-radiative losses are reduced, but device structure becomes more complex
Solution Approach 1:
The passivation layer is implemented as a thin film structure that can be conformally deposited on the side surfaces of the semiconductor chip. This thin film approach provides the necessary passivation function without significantly increasing the overall device volume or structural complexity, as the layer is applied directly to existing surfaces rather than adding bulky components
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The passivation layer significantly reduces non-radiative losses and increases the efficiency of light-emitting diode chips, especially those with a high ratio of side surface to light exit surface, by accumulating charge carriers and bending the band edges, leading to enhanced performance at low current densities.
Implementation Method 1
The statically fixed charges in the passivation layer advantageously lead to a shielding of the oppositely charged type of charge carriers on the side surface
Implementation Method 2
charge carriers with opposite electric charge accumulate in the semiconductor material of the semiconductor layer sequence that adjoins the passivation layer
Implementation Method 3
the statically fixed charges in the passivation layer achieve a bending of the band edge of conduction band and valence band in the semiconductor material of the epitaxial semiconductor layer sequence adjoining the passivation layer
Data Source
AI summary
A light-emitting diode chip and a method for manufacturing a light-emitting diode chip are disclosed. In an embodiment a light-emitting diode chip includes an epitaxial semiconductor layer sequence having an active zone configured to generate electromagnetic radiation during operation and a passivation layer comprising statically fixed electrical charge carriers, wherein the passivation layer is located on a side surface of the semiconductor layer sequence covering at least the active zone.