I did specialization in Intellectual Property Right specially patents and copyright.I do not know what theme/area you actually like. The topic of my PhD was entirely of my choice. So far my knowledge goes I did a passionate choice. So you decide first which area in LIS field you are passionate about. Without passion for a subject you may have a PhD degree, you may have a good marketability but it would not help to contribute to knowledge spectrum in real sense. I strongly believe in that.