Claims
- 1. A method of enhancing the mobility of a narrow bandgap semiconductor material comprising the steps of:
- (a) forming said narrow bandgap material in a first plurality of spaced apart, narrow bandgap semiconductor layers,
- (b) forming a second plurality of wide bandgap semiconductor layers interleaved with and contiguous with said first plurality, and
- (c) forming said wide bandgap layers from a material which (i) is substantially lattice-matched to that of said narrow bandgap layers, (ii) forms a conductor or valence band step at the interfaces with said narrow bandgap layers of sufficient magnitude to confine carriers, and (iii) is doped such that the impurity-concentration-thickness product thereof exceeds that of said narrow bandgap layers.
- 2. The method of claim 1 wherein said forming steps include growing said layers by molecular beam epitaxy in an ultra high vacuum chamber wherein said first and second pluralities of layers are grown alternately on a semiconductor substrate.
- 3. The method of claim 2 wherein said chamber includes an oven carrying a dopant source which is used to generate a donor beam for doping said wide bandgap layers n-type and which is shuttered closed during the growth of said narrow bandgap layers so that impurities are incorporated in said narrow bandgrap layers primarily from background contamination in said chamber.
- 4. The method of claim 3 wherein said forming step (a) is effective to grow said first plurality of GaSa layers having an impurity concentration of about 10.sup.14 or less, and said forming steps (b) and (c) are effective to grow said second plurality of n-type Al.sub.x Ga.sub.l-x As layers 0.02.ltorsim.x having a donor concentration of at least 10.sup.16 /cm.sup.3.
- 5. The method of claim 1 wherein said forming steps (b) and (c) are effective to dope only a central portion of each of said wide bandgap layers with donors, thereby leaving a thin, undoped buffer zone in said wide bandgap layers adjacent said narrow bandgap layers.
Parent Case Info
This application is a division of application Ser. No. 899,402, filed Apr. 24, 1978, now U.S. Pat. No. 4,163,273.
US Referenced Citations (11)
Divisions (1)
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Number |
Date |
Country |
Parent |
899402 |
Apr 1978 |
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