Laser Doping of Chromium and Selenium in p-Type 4H-SiC

Abstract

Chromium (Cr) and selenium (Se) are laser doped in silicon carbide (4H-SiC p-type aluminium) to fabricate an embedded light emitting device and to tune the light emission. A near infrared Nd:YAG (1064 nm wavelength) laser source and an organometallic Cr compound (bis (ethyl benzene)-chromium) and organometallic Se compound (dimethyl selenide) were used to laser dope SiC. A p-n junction device structure was created using these dopants. The dopant profiles have been characterized using secondary ion mass spectrometry. Electrical properties were measured using Hall effect measurement. Enhanced diffusivity and solubility with complete activation of dopants was observed for laser doped Cr and Se. Cr and Se are unconventional dopants, which serve as a double donor and a double acceptor respectively, while aluminium (Al) behaves as single acceptor and nitrogen (N) as a single donor in SiC. The defect levels (donor and acceptor) created within the forbidden band gap of SiC due to Se, Cr and Al onsets the donor acceptor pair (DAP) recombination mechanism for luminescence observed in SiC. Electroluminescence studies showed an orange (677 nm) corresponding to Cr-Al and, red (698 nm) and white (380-900 nm) for Se-Al and pure white for Cr-Se-Al. The Cr-Se-Al white light exhibited a correlated color temperature of 4935 K, which compares well to average daylight (5500 K).