Deposited semiconductor structure to minimize n-type dopant diffusion and method of making

A nonvolatile memory cell formed above a substrate, the memory cell comprising:

• a portion of a bottom conductor above the substrate;
• a portion of a top conductor above the bottom conductor;
• and
• a diode vertically disposed between the bottom conductor and the top conductor, the diode comprising:
• i) a first deposited layer of heavily n-doped semiconductor material;
• ii) a second deposited layer of semiconductor material which is not heavily n-doped wherein the semiconductor material of the second layer is a silicon-germanium alloy that is at least 10 at % germanium, the second layer disposed above and in contact with the first layer;
• and
• iii) a third deposited layer of semiconductor material which is not heavily n-doped, wherein the semiconductor material of the third layer is silicon or a silicon-germanium alloy that is less than 10 at % germanium, wherein the third layer is above and in contact with the second layer.

A monolithic three dimensional memory array comprising:

• a) a first memory level formed above a substrate, the first memory level comprising:
• i) a plurality of substantially parallel, substantially coplanar bottom conductors;
• ii) a plurality of substantially parallel, substantially coplanar top conductors;
• iii) a plurality of semiconductor junction diodes, each diode vertically disposed between one of the bottom conductors and one of the top conductors, wherein each diode comprises a first layer of heavily n-doped semiconductor material, a second layer of lightly n-doped, p-doped, or undoped silicon-germanium alloy wherein the second layer is at least 10 at % germanium, the second layer above the first layer, and a third layer of lightly n-doped, p-doped or undoped silicon or silicon-germanium alloy wherein the third layer is less than 10 at % germanium, the third layer above the second layer;
• and
• b) at least a second memory level monolithically formed above the first memory level.