US 11,990,562 B1
Ultraviolet light-emitting devices having enhanced light output
Leo J. Schowalter, Latham, NY (US)
Assigned to CRYSTAL IS, INC., Green Island, NY (US)
Filed by Leo J. Schowalter, Latham, NY (US)
Filed on Oct. 6, 2021, as Appl. No. 17/494,905.
Claims priority of provisional application 63/088,485, filed on Oct. 7, 2020.
Int. Cl. H01L 33/06 (2010.01); H01L 33/00 (2010.01); H01L 33/32 (2010.01); H01L 33/40 (2010.01)
CPC H01L 33/06 (2013.01) [H01L 33/0075 (2013.01); H01L 33/32 (2013.01); H01L 33/405 (2013.01); H01L 2933/0016 (2013.01)] 14 Claims
OG exemplary drawing
 
1. An ultraviolet (UV) light-emitting device comprising:
a substrate having an AluGa1-uN top surface, wherein 0.4≤u≤1.0;
a bottom contact layer disposed over the substrate, the bottom contact layer comprising AlnGa1-nN;
a light-emitting device structure disposed over the bottom contact layer, the device structure comprising a multiple-quantum well layer comprising a plurality of periods each comprising a strained AlxGa1-xN barrier and a strained AlyGa1-yN quantum well, wherein (i) y is less than x by an amount facilitating confinement of charge carriers in the multiple-quantum well layer, and (ii) y is selected such that light emitted by the multiple-quantum well layer has a wavelength of approximately 240 nm or shorter; and
a cap layer disposed over the multiple-quantum well layer, the cap layer comprising AlwGa1-wN, wherein 0≤w≤0.2,
wherein (i) at least a portion of a sidewall of the light-emitting device structure is angled with respect to a normal to the top surface of the substrate at an angle of approximately a Brewster angle of the light emitted by the multiple-quantum well layer, (ii) the light-emitting device structure is disposed within a mesa disposed over the substrate, at least a portion of the mesa having the sidewall angle, and (iii) the device further comprises a conductive bottom contact disposed over the bottom contact layer and around at least a portion of a base of the mesa.