Long wavelength light emitting device with photoluminescence emission and high quantum efficiency
Various embodiments of light emitting devices with high quantum efficiencies are described herein. In one embodiment, a light emitting device includes a first contact, a second contact spaced apart from the first contact, and a first active region between the first and second contacts. The first active region is configured to produce a first emission via electroluminescence when a voltage is applied between the first and second contacts, and the first emission having a first center wavelength. The light emitting device also includes a second active region spaced apart from the first active region. The second active region is configured to absorb at least a portion of the first emission and produce a second emission via photoluminescence, and the second emission having a second center wavelength longer than the first center wavelength.
1. A light emitting device, comprising:
a first contact, the first contact including a reflective and electrically conductive material;
a first semiconductor material on the first contact;
a second semiconductor material spaced apart from the first semiconductor material;
a first active region between the first and second semiconductor materials, the first active region being configured to produce a first emission via electroluminescence;
a second active region at least proximate the second semiconductor material such that the second semiconductor material is between the first and second active regions, the second active region being configured to absorb at least a portion of the first emission and produce a second emission via photoluminescence;
a third semiconductor material on the second active region; and
a second contact on the third semiconductor material, the second contact including an electrically conductive material, wherein:
the first semiconductor material includes a P-type semiconductor material;
the second semiconductor material includes an N-type semiconductor material; and
the third semiconductor material includes an N-type semiconductor material.
2. A light emitting device, comprising:
a first semiconductor material;
a second semiconductor material spaced apart from the first semiconductor material;
a first active region between the first and second semiconductor materials, the first active region being configured to produce a first emission via electroluminescence;
a second active region at least proximate the second semiconductor material such that the second semiconductor material is between the first and second active regions, the second active region being configured to absorb at least a portion of the first emission and produce a second emission via photoluminescence; and
a third semiconductor material on the second active region, the third semiconductor material and the second material having the same doping type,
wherein the first and second active regions individually include at least one of a bulk indium gallium nitride (“InGaN”) material, an InGaN single quantum well (“SQW”), and GaN/InGaN multiple quantum wells (“MQWs”).
3. A light emitting device, comprising:
a first contact, the first contact including silver (Ag);
a first semiconductor material on the first contact;
a second semiconductor material spaced apart from the first semiconductor material;
a first active region between the first and second semiconductor materials, the first active region being configured to produce a first emission via electroluminescence;
a second active region at least proximate the second semiconductor material such that the second semiconductor material is between the first and second active regions, the second active region being configured to absorb at least a portion of the first emission and produce a second emission via photoluminescence;
a third semiconductor material on the second active region; and
a second contact on the third semiconductor material, the second contact including copper (Cu), wherein:
the first semiconductor material includes P-type gallium nitride (“GaN”);
the second semiconductor material includes N-type GaN; and
the third semiconductor material includes N-type GaN.
4. The light emitting device of claim 3 wherein:
the first and second active regions individually include at least one of a bulk indium gallium nitride (“InGaN”) material, an InGaN single quantum well (“SQW”), and GaN/InGaN multiple quantum wells (“MQWs”);
the first active region having a first composition and a first thickness;
the second active region having a second composition and a second thickness; and
at least one of the first composition and the first thickness is different than the second composition and the second thickness, respectively.
5. A light emitting device, comprising;
a first semiconductor material;
a second semiconductor material spaced apart from the first semiconductor material;
a first active region between the first and second semiconductor materials, the first active region being configured to produce a first emission via electroluminescence;
a second active region at least proximate the second semiconductor material such that the second semiconductor material is between the first and second active regions, the second active region being configured to absorb at least a portion of the first emission and produce a second emission via photoluminescence;
a third semiconductor material on the second active region, the third semiconductor material and the second material having the same doping type;
a first contact; and
a second contact, wherein—
the first semiconductor material is on the first contact, and
the second contact is on the third semiconductor material.
6. The light emitting device of claim 5 , wherein:
the first semiconductor material includes a P-type semiconductor material;
the second semiconductor material includes an N-type semiconductor material; and
the third semiconductor material includes an N-type semiconductor material.
7. The light emitting device of claim 5 wherein the first and second active regions individually include at least one of a single quantum well (“SQW”) and multiple quantum wells (“MQWs”).
8. A light emitting device, comprising:
a first contact;
a second contact spaced apart from the first contact;
a first active region between the first and second contacts, the first active region being configured to produce a first emission via electroluminescence when a voltage is applied between the first and second contacts, the first emission having a first center wavelength;
a second active region spaced apart from the first active region, the second active region being configured to absorb at least a portion of the first emission and produce a second emission via photoluminescence, the second emission having a second center wavelength longer than the first center wavelength; and
a semiconductor material between the first and second active regions, wherein—
the semiconductor material is configured to communicate an electrical current from the second active region to the first active region,
the semiconductor material has a thickness configured to substantially block hole migration from the first active region to the second active region, and
the semiconductor material has a thickness configured to substantially block hole migration from the first active region to the second active region, and
the first and second active regions individually include at least one of a bulk indium gallium nitride (“InGaN”) material, an InGaN single quantum well (“SQW”), and GaN/InGaN multiple quantum wells (“MQWs”).
9. The light emitting device of claim 8 wherein:
the second active region is between the first and second contacts; and
the second active region is insulated from carrier injection from at least one of the first and second contacts.
10. The light emitting device of claim 8 wherein:
the first center wavelength is in one of the blue, violet, or near-ultraviolet wavelength ranges; and
the second center wavelength is in green wavelength ranges.
11. The light emitting device of claim 8 wherein:
the first center wavelength is from about 450 nm to about 500 nm; and
the second center wavelength is from about 495 nm to about 535 nm.
12. The light emitting device of claim 8
the first center wavelength is about 475 nm; and
the second center wavelength is about 510 nm.