How do I generate a ctrl character from my Android phone?

Rebeccah

I have Teamviewer on my laptop already, and recently installed it on my Android phone, to be able to access my Windows PC remotely.  In Windows, the app I especially want to use makes heavy use of ctrl characters.  My phone doesn't have a ctrl key on the built-in virtual keyboard.  How do I do this?

Thanks,

Rebeccah