1. A semiconductor structure on a substrate comprising:
a downwards operating vertical NPN transistor formed on said substrate and having an epitaxial extrinsic base region, an emitter region, and a collector region, and
a downwards-operating vertical PNP transistor formed on said substrate having an epitaxial base region, an emitter region, and a collector region;
wherein said base region of said vertical NPN transistor comprises a first portion of a first layer and said base region of said vertical PNP transistor comprises a second portion of said first layer.
2. The semiconductor structure of claim 1, wherein said first layer comprises epitaxial silicon germanium (SiGe).
3. The semiconductor substrate of claim 1, wherein said epitaxial SiGe includes a first dopant type.
4. The semiconductor substrate of claim 3, wherein said first dopant type includes a p-type dopant.
5. The semiconductor substrate of claim 1, wherein a portion of said emitter of said PNP transistor comprises a portion of said second portion of said first layer.
6. The semiconductor substrate of claim 1, wherein an intrinsic base of said NPN transistor comprises said first portion of said first layer.
7. The semiconductor substrate of claim 1, wherein an extrinsic base of said NPN transistor comprises a first portion of a second layer and the emitter of said PNP transistor comprises a second portion of said second layer.
8. The semiconductor substrate of claim 7, wherein said second layer comprises polysilicon or silicon.
9. The semiconductor substrate of claim 8, wherein said polysilicon or silicon layer comprises a p-type dopant.
10. A semiconductor structure on a substrate comprising a downwards operating vertical PNP transistor formed on said substrate having a base region, an emitter region, and a collector region wherein said collector region of said vertical PNP transistor is formed on a same layer on said substrate as a collector region for a downwards operating vertical NPN transistor.
11. The semiconductor structure of claim 10, wherein said layer comprises epitaxial silicon germanium (SiGe).
12. The semiconductor structure of claim 10, wherein said layer comprises an epitaxial silicon germanium (SiGe) layer or a silicon layer.
13. The semiconductor substrate of claim 10, wherein said layer includes a first dopant type.
14. The semiconductor substrate of claim 13, wherein said first dopant type includes a p-type dopant or an n-type dopant.
15-26. (canceled)
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for preparing a phenolic compound, comprising:
providing a lignin depolymerization product; and
hydrogenating the lignin depolymerization product under iron oxide and hydrogen gas to prepare a phenolic compound.
2. The method for preparing a phenolic compound as claimed in claim 1, wherein the lignin depolymerization product comprises 4-methoxyphenol
o-methoxyphenol
2,6-dimethoxyphenol
or a combination thereof.
3. The method for preparing a phenolic compound as claimed in claim 1, wherein the iron oxide is triiron tetraoxide (Fe3O4).
4. The method for preparing a phenolic compound as claimed in claim 1, wherein the iron oxide has a particle size equal to or less than 5 \u03bcm.
5. The method for preparing a phenolic compound as claimed in claim 1, wherein the lignin depolymerization product is hydrogenated at a temperature of 160-360\xb0 C.
6. The method for preparing a phenolic compound as claimed in claim 1, wherein the lignin depolymerization product is hydrogenated at a pressure of hydrogen gas of 5-100 atm.
7. The method for preparing a phenolic compound as claimed in claim 1, wherein the lignin depolymerization product is hydrogenated at a space velocity of 10-60 h\u22121.
8. The method for preparing a phenolic compound as claimed in claim 1, wherein the phenolic compound is a crude phenolic composition.
9. The method for preparing a phenolic compound as claimed in claim 8, wherein the crude phenolic composition comprises phenol, methylphenol, dimethylphenol or a combination thereof.