It's the \ttdefault command which normally takes care of this.
\documentclass{article}
\begin{document}
\texttt{How to use a typewriter font}% CM default typewriter font
\par
\renewcommand\ttdefault{cmvtt} % selects CM typewriter proportional font
\texttt{How to use a typewriter font}
\par
\renewcommand{\ttdefault}{pcr} % selects Courier font
\texttt{How to use a typewriter font}
\end{document}
But indeed it's usually best to let dedicated packages as beramamono do this, since there can be a lot of subtleties behind fonts (of which I'm often not aware myself :-)
Best Answer
I think this is simply an "e" in a Times clone. Your image seems to have been produced with
mathptmx
.Note however that
mathptmx
is obsolete; if you want to use a Times clone you should usenewtx
instead.