High DC current gain InGaP/GaAs HBTs grown by LP-MOCVD

The high current gain of InGaP/GaAs heterojunction bipolar transistors (HBT s) grown under optimised growth conditions using MOCVD is demonstrated. Lar ge area (60 mum x 60 mum) samples of InGaP/GaAs HBTs are growth and fabrica ted for DC characterisation. These devices show Gummel plots with nearly id eal I-Ti characteristics (n(c) = 1.00 and n(b) = 1.09). Measured current ga in of the devices with a base sheer resistance R-b of 236 Omega /sq is 130 at a collector current I-c of 1mA and 147 at the collector current density of 1kA/cm(2) (I-c = 39.1mA). The current gain to base sheet resistance rati o is 0.623 at 1kA/cm(2), which is the highest value ever reported. The opti mised growth condition improves the current gain in the entire range of the collector current. The current gain is as high as 92 at an I-c of 10 muA. These results are the best that have ever been demonstrated with InGaP/GaAs HBTs. The data show that the MOCVD growth condition is an important factor in achieving high current gain in InGaP/GaAs HBTs.