Single-semiconductor-layer channel in a memory opening for a three-dimensional non-volatile memory device

A three-dimensional memory device, comprising:

• a substrate having a major surface;
• an alternating stack of insulating material layers and control gate electrodes located over the substrate, the alternating stack having a memory opening extending through the alternating stack in a direction substantially perpendicular to the major surface;
• a memory film located at a peripheral region of the memory opening;
• and
• a semiconductor channel including an upper portion extending substantially perpendicular to the major surface and contacting an inner sidewall of the memory film and a lower portion contacting a single crystalline semiconductor material portion located within or on the substrate;
• wherein:
• an outer sidewall of the upper portion of the semiconductor channel is laterally offset with respect to an outer sidewall of the lower portion of the semiconductor channel;
• and
• the semiconductor channel does not include a substantially contiguous interface composed of grain boundaries, not contacting the memory film, and vertically extending through the semiconductor channel between a plurality of control gate electrodes.