A new bias‐enhanced nucleation method of forming highly oriented diamond on Si(100) is reported using an alternating current bias source. The percentage of aligned particles via alternating current bias‐enhanced nucleation (ac BEN) was greater than 50%. This is compared to less than 10% highly oriented particles when using a conventional negative dc substrate bias. Based on previous work in this area, the peak negative voltage portion of the ac wave form is believed to be responsible for enhancing diamond nucleation. The positive and moderate negative voltage portion of the ac wave form appears to aid the process of forming the highly oriented diamond. ©1996 American Institute of Physics.