Technical Insight
RF Nitro debuts GaN HEMT transistors (Nitride News)
RF Nitro Communications, a manufacturer of GaN products based in Charlotte, North Carolina, has introduced its first AlGaN/GaN transistors (see ). The company first demonstrated GaN-based VCOs in February of this year, and has now made available for evaluation prototype transistors fabricated on either sapphire or semi-insulating SiC substrates. Applications for the company s HEMTs, which offer wide bandwidth operation and breakdown voltages approaching 100 V, include high power switching, driver amplifiers, electro-optical modulators and oscillators. To date, RF Nitro has grown GaN devices by MOVPE in an 8 2-inch production reactor (see Compound Semiconductor Sept/Oct 2000, p17). The company says that its AlGaN/GaN-on-sapphire HEMTs offer the advantages of a low cost substrate, and deliver a power density of up to 2 W/mm at 10 GHz. AlGaN/GaN-on-SiC HEMTs dissipate more heat than devices grown on sapphire, and allow higher voltage operation, in addition to a power density of 6.6 W/mm at 10 GHz. "Large-diameter sapphire costs approximately $100 per substrate, and GaN-on-sapphire offers superior insulating properties, lower defect density, higher frequency performance, and superior power performance over GaN-on-silicon approaches," said Joseph Smart, VP of advanced materials. "SiC substrates are expensive, but GaN-on-SiC offers the best combination of frequency and power performance for high-power applications." RF Nitro s NGN-125-D (Al)GaN-on-sapphire device features a coplanar design with a 1 mm periphery and gate length of 0.5 m. Available in die form, the device provides a gain of 9.7 dB and saturated output power of 29 dBm, while the third order intercept (IP3) and noise figure reach +39.5 dBm and 3.5 dB, respectively (at 2 GHz). The cut off and maximum oscillation frequencies (Ft and Fmax) are 16 and 26 GHz, respectively. The company s (Al)GaN-on-SiC HEMT (NGN-225-D series) offers similar performance and features a 1.5 mm periphery, a gain of 8.6 dB and saturated output power of 31 dBm at 10 GHz. The IP3 value is 35 dBm and Ft and Fmax are both 24 GHz. Processing facility completed RF Nitro has also completed a new facility for GaN epitaxy and wafer processing. Located at the company s headquarters in Charlotte, the facility houses class 10 and class 1000 clean rooms intended for the production of GaN-based heteroepitaxial structures and power transistors. The new facility will enable an expansion from 2 inch diameter epiwafer capability to 4 inch epitaxial growth using RF Nitro s patented high-throughput Flow Modulation Epitaxy (FME) technology. According to VP of sales and marketing, B J Lyman, RF Nitro is currently using external foundry facilities to process its chips, and will begin producing 4 inch GaN epiwafers at its Charlotte facility by 2002. "At present we have a prototype production facility that is undertaking high-frequency packaging of GaAs and GaN devices," says Lyman. "All of the NGN series of nitride products are presently at the evaluation stage, and we are now increasing the throughput of these devices to satisfy interest. In the near term, our GaN activity will evolve from discretes to MMICs, available in either chip or packaged form." "This facility is indicative of our commitment to offer our customers a low-cost and high-performance GaN IC technology," added Jeff Shealy, president and CEO. "With this new facility, we will extend our market leadership from GaN epitaxial materials to GaN devices and amplifier circuits for wireless and wireline infrastructure."
