Comparative study on breakdown characteristics for InGaAs metamorphic high electron mobility transistor and InGaAs/InP-composite channel metamorphic high electron mobility transistor

To perform a comparative study, we experimented on two differential epitaxial structures, the conventional metamorphic highelectron-mobility-transistor (MHEMT) using the InAlAs/InGaAs/InAlAs structure and the InP-composite-channel MHEMT adopting the InAlAs/InGaAs/lnP structure. Compared with the conventional MHEMT, the InP-composite-channel MHEMT shows improved breakdown performance; more than approximately 3.8 V. This increased breakdown voltage can be explained by the lower impact ionization coefficient of the InP-composite-channel MHEMT than that of the conventional MHEMT. The InP-composite-channel MHEMT also shows improved Radio Frequency characteristics Of S-21 gain of approximately 4.35 dB at 50 GHz, and a cutoff frequency (f(T)) and a maximum frequency of oscillation (f(max)) of approximately 124 GHz and 240 GHz, respectively, were obtained. These are due to decreases in go and gm.