Some embodiments include an integrated assembly having a first structure containing semiconductor material, and having a second structure contacting the first structure. The first structure has a composition along an interface with the second structure. The composition includes additive to a concentration within a range of from about 1018 atoms/cm3 to about 1021 atoms/cm3. The additive includes one or more of carbon, oxygen, nitrogen and sulfur. Some embodiments include methods of forming integrated assemblies.