Micro light emitting element and its preparation method
The present disclosure provides a micro light-emitting element, method for manufacturing a micro light-emitting element, and a light-emitting device. The micro light-emitting element includes a DBR structure layer, including a DBR adhesive layer, a DBR reflective layer, and a DBR sacrificial layer, where the DBR adhesive layer, the DBR reflective layer, and the DBR sacrificial layer are sequentially stacked. Subsequent structural coverage of a DBR reflective layer is improved by means of the DBR adhesion layer. Density of film layers of the DBR sacrificial layer, the DBR reflective layer, and the DBR adhesive layer are sequentially increased, so that etching rates of the DBR sacrificial layer, the DBR reflective layer, and the DBR adhesive layer are sequentially decreased during etching, thereby forming an inverted trapezoidal through hole which comprises an inclined side wall by an etching process.
1 . A micro light-emitting element, comprising: a substrate and one or more light-emitting diode (LED) array units arranged on a surface of the substrate and isolated from each other by grooves, wherein the one or more LED array units comprise:
an epitaxial laminated layer, comprising a first type semiconductor layer, an active layer, and a second type semiconductor layer, wherein:
the first type semiconductor layer, the active layer, and the second type semiconductor layer are sequentially stacked in a first direction;
a local area of the epitaxial laminated layer is etched to a part of the first type semiconductor layer, resulting in a groove and a mesa; and
the first direction is perpendicular to the substrate, and points from the substrate to the epitaxial laminated layer;
an electrode extension bar stacked on the mesa;
a Distributed Bragg Reflector (DBR) structure layer, comprising a DBR adhesive layer, a DBR reflective layer, and a DBR sacrificial layer, wherein the DBR adhesive layer, the DBR reflective layer, and the DBR sacrificial layer are sequentially stacked along a surface of the epitaxial laminated layer; wherein the DBR structure layer further comprises a first through hole exposing part of a surface of the groove and a second through hole exposing part of a surface of the electrode extension bar;
a first electrode stacked on the first through hole and electrically connected to the first type semiconductor layer; and
a second electrode stacked on the second through hole and electrically connected to the second type semiconductor layer.
2 . The micro light-emitting element according to claim 1 , wherein density of film layers of the DBR sacrificial layer, the DBR reflective layer, and the DBR adhesive layer are sequentially increased, so that etching rates of the DBR sacrificial layer, the DBR reflective layer, and the DBR adhesive layer are sequentially decreased during etching, whereby an inverted trapezoidal through hole is etched, the inverted trapezoidal through hole comprising an inclined side wall.
3 . The micro light-emitting element according to claim 2 , wherein an included angle is between the inclined side wall and a horizontal surface of the epitaxial laminated layer, and wherein a value of the included angle is in a range of 5°-50°, inclusive of endpoint values.
4 . The micro light-emitting element according to claim 3 , wherein a ratio of a thickness of the DBR reflective layer to a thickness of the DBR sacrificial layer is in a range of 1:1 to 1:5; and wherein the thickness of the DBR sacrificial layer increases as the included angle decreases.
5 . The micro light-emitting element according to claim 1 , wherein the mesa further comprises a transparent conductive layer, and the electrode extension bar is stacked on a side surface of the transparent conductive layer facing away from the epitaxial stack layer.
6 . The micro light-emitting element according to claim 1 , wherein the DBR adhesive layer comprises at least one of Ti 3 O 5 , SiO 2 , or Al 2 O 3 , and the DBR adhesive layer is deposited through atomic layer deposition.
7 . The micro light-emitting element according to claim 1 , wherein the DBR sacrificial layer comprises a spin-coated glass layer or an insulating film deposited through low-temperature deposition.
8 . A light-emitting device, comprising:
a driving device, configured to transmit a driving signal to one or more micro light-emitting elements; and
the one or more micro light-emitting elements, wherein each of the one or more micro-lighting elements comprises:
a substrate and one or more light-emitting diode (LED) array units arranged on a surface of the substrate and isolated from each other by grooves, wherein the plurality of LED array units comprise:
an epitaxial laminated layer, comprising a first type semiconductor layer, an active layer, and a second type semiconductor layer wherein:
the first type semiconductor layer, the active layer, and the second type semiconductor layer are sequentially stacked in a first direction;
a local area of the epitaxial laminated layer is etched to a part of the first type semiconductor layer, resulting in a groove and a mesa; and
the first direction is perpendicular to the substrate, and points from the substrate to the epitaxial laminated layer;
an electrode extension bar stacked on the mesa;
a Distributed Bragg Reflector (DBR) structure layer, comprising a DBR adhesive layer, a DBR reflective layer, and a DBR sacrificial layer, wherein the DBR adhesive layer, the DBR reflective layer, and the DBR sacrificial layer are sequentially stacked along a surface of the epitaxial laminated layer; wherein the DBR structure layer further comprises a first through hole exposing part of a surface of the groove and a second through hole exposing part of a surface of the electrode extension bar;
a first electrode stacked on the first through hole and electrically connected to the first type semiconductor layer; and
a second electrode stacked on the second through hole and electrically connected to the second type semiconductor layer.
9 . The light-emitting device according to claim 8 , wherein density of film layers of the DBR sacrificial layer, the DBR reflective layer, and the DBR adhesive layer are sequentially increased, so that etching rates of the DBR sacrificial layer, the DBR reflective layer, and the DBR adhesive layer are sequentially decreased during etching, whereby an inverted trapezoidal through hole is etched, the inverted trapezoidal through hole comprising an inclined side wall.
10 . The light-emitting device according to claim 9 , wherein an included angle is between the inclined side wall and a horizontal surface of the epitaxial laminated layer, and wherein a value of the included angle is in a range of 5°-50°, inclusive of endpoint values.
11 . The light-emitting device according to claim 10 , wherein a ratio of a thickness of the DBR reflective layer to a thickness of the DBR sacrificial layer is in a range of 1:1 to 1:5; and wherein the thickness of the DBR sacrificial layer increases as the included angle decreases.
12 . The light-emitting device according to claim 8 , wherein the mesa further comprises a transparent conductive layer, and the electrode extension bar is stacked on a side surface of the transparent conductive layer facing away from the epitaxial stack layer.
13 . The light-emitting device according to claim 8 , wherein the DBR adhesive layer comprises at least one of Ti 3 O 5 , SiO 2 , or Al 2 O 3 , and the DBR adhesive layer is deposited through atomic layer deposition.
14 . The light-emitting device according to claim 8 , wherein the DBR sacrificial layer comprises a spin-coated glass layer or an insulating film deposited through low-temperature deposition.