Dinh (J Algebra 324:940–950, 2010) characterized constacyclic codes of length ps over R_2= F_{p^m}+ uF_{p^m} , where u^2 = 0. This idea has been generalized to skew constacyclic codes by many authors. In this paper, we provide new methods to characterize the structure of skew cyclic codes of length p^ss over R_2= F_{p^m}+ uF_{p^m}. As a special case, if we restrict our attention to the polynomial rings F_{p^m}[x] and R_2[x], we obtain most of results appeared in the above paper for cyclic codes.
