Method of fabricating semiconductor devices on a group IV substrate with controlled interface properties and diffusion tails
Electronic and opto-electronic devices having epitaxially-deposited III/V compounds on vicinal group IV substrates and method for making same. The devices include an AlAs nucleating layer on a Ge substrate. The group IV substrate contains a p-n junction whose change of characteristics during epitaxial growth of As-containing layers is minimized by the AlAs nucleating layer. The AlAs nucleating layer provides improved morphology of the devices and a means to control the position of a p-n junction near the surface of the group IV substrate through diffusion of As and/or P and near the bottom of the III/V structure through minimized diffusion of the group IV element.
1. A semiconductor device comprising:
a p-type germanium layer;
a nucleating layer formed on the germanium layer, the nucleating layer including a III-V compound selected from the group consisting of AlAs, AlSb, AlN, BAs, BSb, GaN, GaSb, and InAs; and
a first III-V compound layer formed on the nucleating layer, the first III/V compound layer including at least one of GaInP, AlInP, and AlGaInP, the p-type germanium layer having diffused therein phosphorous atoms from the first III-V compound layer, a concentration of the phosphorous atoms diffused in the p-type germanium layer being a function of a thickness of the nucleating layer, the first III-V compound layer having diffused therein germanium atoms from the p-type germanium layer, a concentration of the germanium atoms diffused in the first III-V compound layer being a function of the thickness of the nucleating layer, the semiconductor device having a morphology that is substantially defect-free.
2. The device of claim 1 further comprising a second III-V compound layer formed on the first III/V compound layer.
3. The device of claim 2 wherein, the second III-V compound layer includes GaAs.
4. The device of claim 2 wherein, at least one of the nucleating layer, the first III/V compound layer and the second III/V compound layer is formed by an epitaxial growth process.
5. The device of claim 1 wherein, the p-type germanium layer has a p-n junction proximate the nucleating layer.
6. The device of claim 1 wherein, the device is an electronic device.
7. The device of claim 6 wherein, the electronic device is an opto-electronic device.
8. The device of claim 7 wherein, the opto-electronic device is a solar cell or a light emitting diode.
9. The device of claim 1 wherein, the p-type germanium layer is a p-type germanium substrate.
10. The device of claim 9 wherein, the p-type germanium substrate is a vicinal substrate.
11. The device of claim 10 wherein, the vicinal substrate has an angle ranging from 0° to 20°.
12. The device of claim 1 wherein, the thickness of the nucleating layer ranges from 1 to 20 monolayers.
13. The device of claim 1 wherein the germanium atomic concentration is less than, 1×10 18 cm −3 at a distance of substantially 150 nm from the nucleating layer.
14. The device of claim 1 wherein the concentration of the group V atoms diffused from the first III-V compound layer into the p-type germanium layer is less than, or substantially equal to, 1×10 18 cm −3 at a distance of substantially 600 nm from the nucleating layer.
15. A method of fabricating a semiconductor structure on a p-type germanium layer, the method comprising steps of:
forming a nucleating layer on the germanium layer, the nucleating layer including a III-V compound selected from the group consisting of AlAs, AlSb, AlN, BAs, BSb, GaN, GaSb, and InAs; and
forming a first III-V compound layer on the nucleating layer, the first III/V compound layer including at least one of GaInP, AlInP, and AlGaInP, the p-type germanium layer having diffused therein phosphorous atoms from the first III-V compound layer, a concentration of the phosphorous atoms diffused in the p-type germanium layer being a function of a thickness of the nucleating layer, the first III-V compound layer having diffused therein germanium atoms from the p-type germanium layer, a concentration of the germanium atoms diffused in the first III-V compound layer being a function of the thickness of the nucleating layer, the semiconductor device having a morphology that is substantially defect-free.
16. The method of claim 15 further comprising a step of forming a second III/V compound layer structure on the first III/V compound layer.