Light emitting diode chip

• US 8,198,648 B2
• Filed: 06/09/2008
• Issued: 06/12/2012
• Est. Priority Date: 06/20/2007
• Status: Expired due to Fees

• Current Assignee: Optogan Oy
• Original Assignee: Optogan Oy
• Inventors: Bougrov, Vladislav E., Odnoblvudov, Maxim A.
• Primary Examiner(s): Louie, Wai Sing
• Assistant Examiner(s): Jahan, Bilkis
• Application Number:
  US12/667,330
• Publication Number:
  US 20100163910A1
• Time in Patent Office: 1,464 Days
• Field of Search: 257/91, 257/81, 257/84, 257/88, 257/93, 257/94, 257/99, 257/690, 257/698, 257/700
• US Class Current: 257/98
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/38 with a particular shape

Abstract

An LED chip (1) grown on an electrically insulating substrate (4) comprises a lower current-distributing layer (5) of a first conductivity type, a first electrode (2), a vertical layer structure (5, 6, 7), the last two being formed on the lower current-distributing layer horizontally separated from each other, the vertical layer structure comprising an active layer (6) and an upper current-distributing layer (8) of a second conductivity type above the active layer, and a second electrode (3) formed on the upper current-distributing layer, the geometry of the electrodes being adjusted to provide a horizontal distance between the electrodes lower than the current spreading length of the chip. According to the present invention, a vertical trench (9) is formed between the electrodes (2, 3), the trench extending through the chip (1), including the lower current-distributing layer (5), for controlling the horizontal current flow in order to achieve a uniform current density over the active layer (6).

Claims

1. An LED chip grown on an electrically insulating substrate, the LED chip comprising a lower current-distributing layer of a first conductivity type, a first electrode, a vertical layer structure, the last two being formed on the lower current-distributing layer horizontally separated from each other, the vertical layer structure comprising an active layer and an upper current-distributing layer of a second conductivity type above the active layer, and a second electrode formed on the upper current-distributing layer, the geometry of the first and second electrodes being adjusted to provide a horizontal distance between the first and second electrodes lower than the current spreading length of the chip, characterized in that a vertical trench is formed between the electrodes, the trench extending through all layers of the chip, including the lower current-distributing layer, for controlling the horizontal current flow in order to achieve a uniform current density over the active layer.

2. An LED chip according to claim 1, characterized in that an additional vertical trench is formed between the electrodes, the additional trench extending through the chip, including the active layer, along the direction of the horizontal current flow in the current-distributing layers for increasing the overall perimeter of the vertical layer structure and thus enhancing the light extraction from the chip.

3. An LED chip according to claim 1, characterized in that a side wall of the vertical layer structure is tilted from the vertical direction for facilitating the light extraction from the chip.