I may be a little late to the party, but I think CJBS (see comment on Akram) is right. Unfortunately, I cannot make a comment, so I will post this as an answer (which should also be good, because I give an answer).
Since the OP answer already answered, I will give an answer that will help people with the same question:
This will make the button text larger:
android:textSize=""
This will increase the height of the button:
android:height=""
This will make the button wider:
android:width=""
EDIT:
Using 'min' to 'width' or 'height' might also be a good idea.
Example:
android:minWidth=""
user4621049
source share