I guess the first novel I read on Irish history was Leon Uris' Trinity. The time frame is much broader than just the famine years, but it gave me a good sense of cause/effect of many Irish events. Trinity was hard for me to read: it was so much like watching a close relative die slowly.... He later wrote a sequel called Redemption. Also, several years ago, making a similar request to yours, an Irish professor/archaeologist recommended to me a trilogy by Walter Macken: Seek the Fair Land, The Silent People [which is the one that deals directly with the famine], and The Scorching Wind. Good stuff.