Single crystalline silicon stack formation and bonding to a cmos wafer

A method, comprising:

• forming a first layer of single crystal silicon germanium onto a surface of a first substrate;
• forming a first layer of single crystal silicon onto a surface of the single crystal silicon germanium;
• forming, in repeating iterations, a number of additional layers of single crystal silicon germanium and single crystal silicon to form a vertical stack of alternating single crystal silicon and single crystal silicon germanium layers;
• and
• bonding a surface of the vertical stack to a second substrate.

A method, comprising:

• forming a vertical stack of repeating iterations of single crystal silicon germanium and single crystal silicon layers on a substrate, wherein the vertical stack includes at least two iterations, and wherein forming each iteration comprises:
• forming a seed layer of single crystal silicon germanium;
• epitaxially growing single crystal silicon germanium from the seed layer of crystal silicon germanium to a desired first thickness;
• forming a seed layer of single crystal silicon onto a surface of the epitaxially grown single crystal silicon germanium;
• and
• epitaxially growing single crystal silicon from the seed layer of single crystal silicon to a desired second thickness;
• and
• forming dynamic random access memory cells in the vertical stack.