Assemblies Having Vertically-Extending Structures, and Methods of Forming Assemblies Having Vertically-Extending Channel Material Pillars

An assembly, comprising:

• channel material pillars which extend vertically;
• memory cells along the channel material pillars;
• a conductive structure under the channel material pillars and comprising doped semiconductor material in direct contact with bottom regions of the channel material pillars;
• one or more of magnesium, scandium, yttrium and lanthanide elements along the bottom regions of the channel material pillars;
• and
• wherein said one or more of the magnesium, the scandium, the yttrium and the lanthanide elements are within annular structures which extend around the bottom regions of the channel material pillars.

An assembly comprising:

• a horizontally-extending structure comprising a first semiconductor material;
• one or more vertically-extending structures over the horizontally-extending structure and comprising a second semiconductor material;
• the second semiconductor material of said one or more vertically-extending structures directly contacting the first semiconductor material of the horizontally-extending structure along terminal ends of the one or more vertically-extending structures;
• said terminal ends of the one or more vertically-extending structures being comprised by bottom regions of the one or more vertically-extending structures;
• and
• scandium along the bottom regions of the one or more vertically-extending structures.

An assembly comprising:

• a horizontally-extending structure comprising a first semiconductor material;
• one or more vertically-extending structures over the horizontally-extending structure and comprising a second semiconductor material;
• the second semiconductor material of said one or more vertically-extending structures directly contacting the first semiconductor material of the horizontally-extending structure along terminal ends of the one or more vertically-extending structures;
• said terminal ends of the one or more vertically-extending structures being comprised by bottom regions of the one or more vertically-extending structures;
• one or more of magnesium, scandium, yttrium and lanthanide elements along the bottom regions of the one or more vertically-extending structures;
• and
• wherein said one or more of the magnesium, the scandium, the yttrium and the lanthanide elements are within annular structures which extend around the bottom regions of the one or more vertically-extending structures.