How much does "having publications" mean to a undergraduate direct-PhD applicant?
While I can't comment about microelectronics or EE specifically, I should point out that many US graduate schools admit external candidates only to a Ph.D. program; there is no option available for admission to a master's program en route to a doctoral program. Consequently, the students met the requirements for admission to the school, period. 

Research experience is always helpful, particularly because it gives you a potential letter of reference from someone who can directly comment on your skills as a researcher, which is the biggest thing that graduate departments are looking for. They want candidates who are capable of doing high-quality research, and having confirmation of that—whether or not there are papers already written—is a vital component of that process.

I would also suggest it's probably not worth it to try to compete with faceless peers whose credentials you can't guess. That's a hopeless endeavor that will just make you frustrated and dispirited. Just do the best job that you can with the resources available to you, rather than worrying about "keeping up with the Joneses."