Methods of fabricating integrated circuit device with fin transistors having different threshold voltages are provided. The methods may include forming first and second semiconductor fins including first and second semiconductor materials, respectively, and covering at least one among the first and second semiconductor fins with a mask. The methods may further include depositing a compound semiconductor layer including the first and second semiconductor materials directly onto sidewalls of the first and second semiconductor fins not covered by the mask and oxidizing the compound semiconductor layer. The oxidization process oxidizes the first semiconductor material within the compound semiconductor layer while driving the second semiconductor material within the compound semiconductor layer into the sidewalls of the first and second semiconductor fins not covered by the mask.