Light emitting diodes containing deactivated regions and methods of making the same
A light emitting device (LED) includes an n-doped semiconductor material layer, an active region including an optically active compound semiconductor layer stack configured to emit light located on the n-doped semiconductor material layer, a p-doped semiconductor material layer located on the active region, an anode contact contacting the p-doped semiconductor material layer, a reflector overlying and electrically connected to the anode contact, and a device-side bonding pad layer located on the reflector. The p-doped semiconductor material layer includes an electrically active region that is at least partially covered by the anode contact and an inactive region that an electrical conductivity less than 30% of the electrically active region.
1 . A method of forming a light emitting diode (LED), comprising:
forming a single crystalline buffer semiconductor layer on a support substrate to have a graded composition such that a first composition of the single crystalline buffer semiconductor layer at an interface with the support substrate matches a structure of a top surface of the support substrate;
forming an n-doped semiconductor material layer on a top surface of the single crystalline buffer semiconductor layer to match a second composition of the single crystalline buffer semiconductor layer at the top surface of the single crystalline buffer semiconductor layer;
forming an active region including an optically active compound semiconductor layer stack configured to emit light on the n-doped semiconductor material layer;
forming a p-doped semiconductor material layer on the active region;
deactivating a physically exposed portion of the p-doped semiconductor material layer with a plasma treatment to form an inactive region while an electrically active region remains in the p-doped semiconductor material layer that is not subjected to plasma during the plasma treatment;
forming an anode contact on the p-doped semiconductor material layer;
forming a reflector overlying and electrically connected to the anode contact; and
forming a device-side bonding pad layer on the reflector.
2 . The method of claim 1 , wherein the plasma treatment structurally damages a crystalline structure of the inactive region.
3 . The method of claim 1 , wherein the plasma treatment applies the plasma selected from a hydrogen plasma, an oxygen plasma, and a nitrogen plasma to the physically exposed surface portion of the p-doped semiconductor material layer.
4 . The method of claim 1 , wherein the inactive region has a lesser thickness than a thickness of the electrically active region.
5 . The method of claim 1 , wherein:
the p-doped semiconductor material layer comprises a magnesium doped gallium nitride layer; and
the inactive region and the electrically active region comprise portions of the magnesium doped gallium nitride layer that are doped with magnesium at the same atomic concentration.
6 . The method of claim 1 , further comprising:
forming a mask over the p-doped semiconductor material layer such that the mask covers the electrically active region and exposes the inactive region;
exposing the masked p-doped semiconductor material layer to the plasma treatment to deactivate the physically exposed inactive region while the masked electrically active region is not exposed to the plasma treatment; and
removing the mask prior to forming the anode contact.
7 . The method of claim 1 , further comprising bonding multiple instances of the LED on a backplane in an array configuration, wherein each of the LEDs comprises a micro LED subpixel of a direct view display device.
8 . The method of claim 1 , further comprising applying an operating voltage to the LED to produce a current density in the LED which generates light emission at an external quantum efficiency in a range from 0.9 times of a peak external quantum efficiency of the LED to the peak external quantum efficiency of the LED.