• Isoird, Karine
• Pinault-Thaury, M. A.
• Bouras, Mohamed
• Planson, Dominique
• Jomard, François
• Barjon, Julien
• Phung, Luong Viêt
• Achard, Jocelyn
• Chikoidze, Ekaterina
• Issoui, Riadh
• Gourad, Raid
• Sonneville, Camille
• Cazarré, Alain
• Stenger, Ingrid
• Mesples-Carrere, Rémi
• Kociniewski, Thierry
• Arvizu, Ken Castillo
• Tasselli, Josiane
• Gillet, Rémi

Abstract

Among conventional diamond orientations, (100) is preferred for future diamond electronics applications. Indeed, (100) diamond substrates are easier to polish, less expensive to produce and are believed to present better electronic quality. Moreover, the control of diamond’s doping for electronics is asymmetric as for other wide band gap semiconductors (e.g. GaN). The p-type doping of diamond by substituting boron to carbon is fairly easy and technologically mature. In contrast, the n-type conductivity of diamond is still difficult to realize. Even if phosphorus is the donor impurity in diamond that gives the highest n-type conductivities, n-type diamond remains an issue for the fabrication of diamond-based bipolar devices. This can explain that diamond community is more active on transistor than on pin (p-intrinsic-n) diode while this is essential for the emergence of diamond electronics.Over last decades diamond quality has been improved thanks to progress made in microwave plasma assisted chemical vapor deposition. In the case of boron p-type diamond, we find growth conditions allowing to grow thick and enlarged homoepilayers. The thickness was managed to be thick enough to separate the homoepilayer from the substrate thanks to laser cutting and polishing. We are now able to fabricate on demand freestanding p+-type diamond films. For phosphorus n-type homoepilayers, we found growth parameters allowing smooth surface with full incorporation of phosphorus in donor sites. We demonstrate that the miscut angle of the substrate is a crucial parameter.In this work, vertical bipolar power devices such as pin diodes were chosen as test structures. We made simulations (TCAD Finite Element Method) to determine the appropriate n+/n- stacking layers on p+ substrate to aim 2.5 kV of breakdown voltage. A dedicated boron-doped (~1020 B/cm3) p+ (100) freestanding film (~3x3 mm²) was fabricated with 3.5° of miscut angle for the following phosphorus doped homoepilayers. We develop growth engineering to ensure sharp interface between n+ and n- epilayers. The resulting structure was analysed by secondary ion mass spectrometry to determine the doping content and the thicknesses of the n+ and n- layers (230 nm with 2.5x1019 P/cm3 on top of 2240 nm with 2.3x1015 P/cm3). Fabrication of large area circular pin diodes (Φ= 200 µm) is under progress with classical Ti/Pt/Au as metal contact. Room temperature I(V) measurements under probes will follow: in forward mode, the current will be limited to an equivalent current density of 50 A/cm², while in reverse mode, the voltage will be progressively increased until a current of 50 nA. Such measurements will allow diodes mapping and cautious screening to avoid damaging. For diodes presenting highest electrical performances, optical beam induced current measurements will be done without voltage to evaluate sample properties (e.g. defects). We will show the full study and the main results obtained so far.

Topics

• density
• impedance spectroscopy
• surface
• Carbon
• simulation
• semiconductor
• laser emission spectroscopy
• defect
• Boron
• current density
• spectrometry
• chemical vapor deposition
• Phosphorus
• secondary ion mass spectrometry
• polishing