Prospects of III-nitride optoelectronics grown on Si

Abstract

The use of III-nitride-based light-emitting diodes (LEDs) is now widespread in applications such as indicator lamps, display panels, backlighting for liquid-crystal display TVs and computer screens, traffic lights, etc. To meet the huge market demand and lower the manufacturing cost, the LED industry is moving fast from 2 inch to 4 inch and recently to 6 inch wafer sizes. Although Al2O3 (sapphire) and SiC remain the dominant substrate materials for the epitaxy of nitride LEDs, the use of large Si substrates attracts great interest because Si wafers are readily available in large diameters at low cost. In addition, such wafers are compatible with existing processing lines for 6 inch and larger wafers commonly used in the electronics industry. During the last decade, much exciting progress has been achieved in improving the performance of GaN-on-Si devices. In this contribution, the status and prospects of III-nitride optoelectronics grown on Si substrates are reviewed. The issues involved in the growth of GaN-based LED structures on Si and possible solutions are outlined, together with a brief introduction to some novel in situ and ex situ monitoring/characterization tools, which are especially useful for the growth of GaN-on-Si structures.

Chemistry of Ammonothermal Synthesis

“…GaN and AlN are semiconductors with wide band gaps used as base for optoelectronic and electronic devices (e.g., light-emitting diodes (LEDs), high electron mobility transistors, lasers with high optical storage capacity). The growth of group III nitrides as bulk crystal is much more difficult than as micro crystalline powder, but necessary for the use in optoelectronic and electronic devices [34,35].…”

Physical Properties and Characteristics of III-V Lasers on Silicon

“…Currently GaN LED wafers are produced with a diameter of only 2 or 3 in due to the difficulty of growing sapphire or SiC wafers of sufficient crystalline quality on a larger scale. The use of 6 in wafers is found to increase device yield by 44% for an equivalent amount of material, greatly reducing cost [27]. Si, being one of the most abundant elements on Earth and already in mass production is an inherently cheaper substrate material to start with.…”

“…Si, being one of the most abundant elements on Earth and already in mass production is an inherently cheaper substrate material to start with. GaN/Si LEDs have not only been realised but are even approaching the performance of those on more standard substrates [27] and have recently been commercialised through Plessey Semiconductors in the UK [28]. Thus it is clear that the integration of III-V materials on silicon substrates has many important applications in photonics.…”

Development of AlGaN/GaN/SiC high-electron-mobility transistors for THz detection

“…Although the first high-electron-mobility transistors (HEMTs) and Schottky diodes (SDs) have been demonstrated on the AlGaN/GaN grown on a native GaN substrate [5], its further development is limited by the high price and small volume production of the GaN crystals. Thus, to make progress in the GaN technology, AlGaN/GaN structures grown on foreign substrates such as silicon [6], sapphire [7], and SiC [8] have been explored. Usually the AlGaN/GaN structures with less demanding performance are fabricated on sapphire or silicon substrates.…”

“…Usually the AlGaN/GaN structures with less demanding performance are fabricated on sapphire or silicon substrates. However, such devices suffer from a larger amount of defects and wafer bending caused by the mismatch of the lattice constant and the difference in the coefficient of thermal expansion [6,9]. On the other hand, AlGaN/GaN HEMTs on a semiinsulating SiC (SI SiC) substrate exhibit a superior performance due to a smaller lattice mismatch and significantly higher thermal conductivity both of which are of vital importance for high power applications [2].…”