You must have the intent to commit fraud before actions of this type are considered a crime. One is not convicted of a crime for making an honest mistake. In order for you to be charged with a crime, you usually would have to get some gain from what you did. If you where to get a "kick back" from the employees, that might be a crime. But here, you probably made a simple mistake.
As the above Attorney has indicated, in order to be convicted of a federal crime, the government must first prove that you had the intent to commit the crime. In your case, it sounds like you did not. Several things to consider are whether you had the authority to authorize the raises, whether the were justified, and whether you personally gained a financial benefit.
This answer is for educational purposes only and should not be construed as legal advice.
I agree with my two, learned colleagues. If this was a situation where a 'kickback' was involved, then you would have cause for concern. However, based upon your statement, above, this appears to be a mere mistake.