Future Trends in Microelectronics

2.5

Group IV Alloys for Advanced Nano- and Optoelectronic Applications

Detlev Grützmacher

Peter Grünberg Institut-9 and JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

1 Introduction

Mainstream semiconductor technology builds on elements of group IV within the periodic table. Crystalline silicon remains the principal base material, whereas germanium and carbon have entered the mainstream in the embedded source/drain technology, as well as in heterojunction bipolar transistors (HBTs) used in BiCMOS technology. Tin, the next group IV element in the periodic table, is a semimetal in its α-Sn phase with a negative bandgap of about 0.4 eV. Most interestingly, group IV alloys containing Sn, in particular Ge_1−xSn_x alloys, have been predicted to be direct bandgap semiconductors.¹

Recently, it has been shown that alloying Ge with Sn enables the fabrication of fundamental direct bandgap group IV semiconductors, as well as optically pumped GeSn lasers grown on Si(001).² This achievement might pave the route toward efficient and monolithically integrated group IV light emitters, that is, lasers, for electronic–photonic integrated circuits (EPICs) that could solve the emerging power consumption crisis in complementary metal-oxide semiconductor (CMOS) technology by enabling optical on-chip and chip-to-chip data transfer. The clock distribution via copper lines takes about 30% of the energy consumption of modern CPU's and the limited bandwidths and delay times are problematic ...