This collection of scientific papers by Ivan Clifford Hall includes some of his most influential work on the properties of semiconductors and the functioning of photovoltaic devices. Hall was a pioneer in the field of renewable energy research, and his contributions have had a lasting impact on the development of solar technology. This book is an essential resource for anyone interested in the science of solar energy. This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work is in the "public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.