Use tag_etc etc

Hi all.

I am trying to organise my tag template pages to display an image at the top of the tag archive page that is specific to each tag. At the moment I am using <?php single_tag_title(); ?> within the call for the image and that is working BUT that presents messy image name using punctuation etc.

Really I want to call the tag slug instead of the title but I just can’t make it work!

I am sure I am doing something stupid but have tried all the obvious ones I could think of and have searched the codex for stuff on tag_etc but can’t find anything.

Any chance someone could point me to the right place?!

Cheers.
Andy.