Ginger in biscotti...I put crystallized ginger in biscotti, and can't taste it. Can raw ginger be used?

You can put many things in twice baked cookie dough, but fresh ginger will disappear faster than candied. Look for organic ground dried ginger in your local health food store or order it in a small quantity (less than 200g) from a trusted source like Kalustyan's or Frontier. When a spice is fresh, and organic, it really shines!

My experience is that not all candied ginger is potent. The darker & the chunkier the piece, the more flavor it tends to have. But I'm not always a fan of dried fruit in biscotti. It tends to harden quite a bit, or worse - burn at the edges where its exposed to heat.

I love the idea of coffee and ginger as a combination. I have also paired ginger with sesame in biscotti to nice affect.

Thanks to every answer! Looks like I'm going to be making a lot of biscotti!

One of my favorite biscotti recipes is Maida Heatter's ginger biscotti. Here it is: https://www.washingtonpost.com/archive/lifestyle/food/1992/12/16/biscotti/22735a5b-9d3c-4511-8417-7a17ef80a603/

yes, you can use both. I do think you should up your candied ginger amount.excellent idea, btw. i love coffee and ginger; wonder if you might try espresso powder in part of your ginger batch. one of the nice things about biscotti is that it is easy to make a base and then quarter it (or more) and flavor @ quarter differently. I would rec you add orange zest or candied orange peel to your cranberry combo. mission figs or prunes or lemon zest are also fun to pair with coffee or ginger. then, of course, there are herbs; thyme and rosemary are prob the most popular for combining w/ citrus and/or other flavors. The Quarters idea is great because if something doesn't really work for you, you only lost 1/4 of the batch, not the whole thing, and maybe another quarter is such a winner- it makes up for all the others!
Here's my recipe that demonstrates that idea:
https://food52.com/recipes/21181-four-way-brownies

how small were the bits? I do frequently make biscotti with crystallized ginger in maybe 1/4 inch bits and can definitely taste it. It is subtler than cranberries though. That said, different brands have different amounts of sugar and bite! https://food52.com/recipes/9294-not-quite-savory-not-quite-sweet-cardamom-ginger-biscotti

I've had luck with crystallized ginger in biscotti, but when baked it does get very sweet. You could try a combination of fresh and crystallized! Want to try my recipe? It's technically for mandelbrot, but the two cookies are VERY similar: http://spicesandspatulas.com/2015/10/28/olive-oil-mandelbrot/

This cookie recipe uses are three types https://food52.com/blog/9222-whole-wheat-triple-ginger-ginger-snaps

But have you tried ground ginger powder? I would put raw ginger but I like the taste and texture.