Development language choice

I want to start developing web applications as a business - not just simple web design, but industrial grade applications. I 'spose it's the difference a simple app and a web site like Dev Shed.
The main problem I have is I'm not entirely happy with PHP as a language and would prefer to use Java. Do people think that it would affect the potential market I could write for.

Of course. You'll only be able to sell applications to clients who can deploy your technology on their servers.

Not sure what you mean by having to deploy it on their servers.
I looked around at hosting companies that provide Tomcat hosting. Although they seemed more expensive than ones hosting php, I didn't see much else in it. Is there something I should look at when hosting a Tomcat application which your aware of?

All I mean is if you write an application that requires tomcat, for example, you won't be able to provide your application to organizations that already have web servers that don't happen to support tomcat.

I was merely answering your question, of course your technology choice will impact your potential market.