1. A method of manufacturing a light emitting diode, comprising the steps of:
(a) forming a buffer layer on a substrate;
(b) forming an n-type electrode layer on the buffer layer, the n-type electrode layer with a multi-layer structure including an n-type current spreading layer using a hetero-junction structure;
(c) forming an active layer on the n-type electrode layer; and
(d) forming a p-type electrode layer on the active layer, the p-type electrode layer with a multi-layer structure including a p-type current spreading layer using a hetero-junction structure.
2. The method according to claim 1, further comprising the steps of:
(e) etching the p-type electrode layer after forming the p-type electrode layer, to expose the n-type current spreading layer of the n-type electrode layer;
(f) forming n- and p-type trenches in the p-type current spreading layer and the n-type current spreading layers exposed by the etching, respectively;
(g) inserting metal electrode layers into the respective trenches to form n- and p-type metal electrode layers; and
(h) forming a transparent electrode layer on the p-type metal electrode layer.
3. The method according to claim 2, wherein step (b) comprises:
(b1) forming an n-GaN layer for supplying electrons;
(b2) forming the n-type current spreading layer with a hetero-junction structure of AlGaNGaN on the n-GaN layer; and
(b3) forming an n+-GaN layer on the n-type current spreading layer.
4. The method according to claim 2, wherein step (d) comprises:
(d1) forming a p-GaN layer for supplying holes;
(d2) forming the p-type current spreading layer with a hetero-junction structure of p-AlGaNGaN on the p-GaN layer; and
(d3) forming a p-type barrier layer on the p-type current spreading layer.
5. The method according to claim 3, wherein each thickness of the n- and p-type trenches ranges from one to three periods of the hetero-junction structure.
6. The method according to claim 4, wherein the p-type barrier layer comprises a p+-AlGaN layer having a thickness of 30\u02dc100 \u212b.
7. The method according to claim 1, wherein the AlGaNGaN hetero-junction structure comprises an undoped AlGaN layer and a GaN layer doped with Si to use the n-type current spreading layer as a two-dimensional electron gas layer.
8. The method according to claim 1, wherein the p-AlGaNGaN hetero-junction structure comprises a p-AlGaN layer doped with Mg less than 1017cm\u22123 and a GaN layer doped with Mg more than 1017cm\u22123 to use the p-type current spreading layer as a two-dimensional hole gas layer.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. An internal combustion engine adapted to drive a propulsion unit, the engine comprising a crankcase at least partially enclosing a crankshaft, a cylinder block having at least one cylinder bore having an uppermost wall portion, a piston arranged within the cylinder bore to reciprocate therein, and a lubrication system, the lubrication system comprising a first lubricant insertion port and a second lubricant insertion port, the first port being positioned and arranged so as to direct lubricant into the crankcase, the second port opening into the cylinder bore, the second port opening through the uppermost wall of the cylinder bore.
2. The engine of claim 1, wherein the crankshaft is substantially vertically disposed, and the cylinder bore is substantially horizontally disposed.
3. The engine of claim 1, wherein the piston includes at least one circumferentially disposed ring, and the second port opens into the cylinder bore at a position so that when the piston is at the bottom dead center position, the second port opens adjacent the piston ring, and when the piston is at the top dead center position, the second port opens into the cylinder bore and does not open onto the piston.
4. The engine of claim 3, wherein the piston includes a second circumferentially disposed ring, and the second port opens into a space between the rings when the piston is at the bottom dead center position.
5. The engine of claim 1, wherein the first lubricant port opens into an air intake upstream of the crankcase.
6. The engine of claim 1, wherein the first lubricant port opens directly into the crankcase.
7. The engine of claim 1, wherein the piston is connected to the crankshaft by a connecting rod, and a piston pin connects the piston to the connecting rod, and wherein the piston is arranged so that lubricant from the second port is injected onto the piston pin as the piston moves past the second port.
8. The engine of claim 1, wherein the lubrication system additionally comprises a lubricant pump, the pump having a first delivery port for delivering lubricant to the first lubricant insertion port and a second delivery port for delivering lubricant to the second lubricant insertion port.
9. The engine of claim 8, wherein a volume of lubricant supplied through the first delivery port is different than a volume of lubricant supplied through the second delivery port.
10. The engine of claim 9, wherein a volume of lubricant supplied through the first delivery port is greater than a volume of lubricant supplied through the second delivery port.
11. The engine of claim 1, wherein the lubrication system additionally comprises a first lubricant pump and a second lubricant pump, the first lubricant pump configured to deliver lubricant to the first lubricant insertion port and the second lubricant pump configured to deliver lubricant to the second lubricant insertion port.
12. The engine of claim 11, wherein one of the lubricant pumps is a mechanical pump and another other of the lubricant pumps is an electromagnetic pump.
13. The engine of claim 1 in combination with a marine drive comprising a marine propulsion device.
14. An internal combustion engine configured to drive a propulsion device, the engine comprising a cylinder block having at least one cylinder formed therein, a cylinder liner disposed in the cylinder and defining a cylinder bore, a piston arranged within the cylinder bore to reciprocate therein, a lubricant discharge port formed through the cylinder block and opening into the cylinder, a circumferential passage formed between the cylinder and the cylinder liner, the circumferential passage arranged so as to communicate with the cylinder block lubricant discharge port, and at least one lubricant delivery hole formed through the cylinder liner and positioned to correspond with the circumferential passage, the delivery hole being offset from the lubricant discharge port.
15. The engine of claim 14, wherein the circumferential passage comprises a groove formed around an outer surface of the cylinder liner.
16. The engine of claim 14, wherein the cylinder has an uppermost wall portion, and one of the lubricant delivery holes is positioned in the uppermost wall portion.
17. An internal combustion engine adapted to drive a propulsion unit, the engine comprising a crankcase at least partially enclosing a crankshaft, a cylinder block having at least one cylinder bore, a piston arranged within the cylinder bore to reciprocate therein, and a lubrication system, the lubrication system comprising means for delivering a first volume of lubricant to engine components in the crankcase and separately delivering a second volume of lubricant to engine components within the cylinder bore.