Germanium Based Field-Effect Transistors: Challenges and Opportunities

Abstract

The performance of strained silicon (Si) as the channel material for today’s metal-oxide-semiconductor field-effect transistors may be reaching a plateau. New channel materials with high carrier mobility are being investigated as alternatives and have the potential to unlock an era of ultra-low-power and high-speed microelectronic devices. Chief among these new materials is germanium (Ge). This work reviews the two major remaining challenges that Ge based devices must overcome if they are to replace Si as the channel material, namely, heterogeneous integration of Ge on Si substrates, and developing a suitable gate stack. Next, Ge is compared to compound III-V materials in terms of p-channel device performance to review how it became the first choice for PMOS devices. Different Ge device architectures, including surface channel and quantum well configurations, are reviewed. Finally, state-of-the-art Ge device results and future prospects are also discussed.

Monolithic integration of perovskites on Ge(001) by atomic layer deposition: a case study with SrHfxTi1-xO3

“…[1] Germanium has electron and hole mobility of 3900 and 1900 cm 2 /Vs, respectively, compared with 1400 and 470 cm 2 /Vs at 300 K, respectively, in Si. For this reason, Ge is being considered for p-type metal-oxide semiconductor field effect transistors (MOSFETs).…”

“…For this reason, Ge is being considered for p-type metal-oxide semiconductor field effect transistors (MOSFETs). [1,2] There are multiple considerations in selecting a gate oxide material including the dielectric constant, band offset, leakage current, interface trap density (D it ), and ease of manufacturing. [3,4] Various groups have reported gate oxides on Ge in MOSFETs, including TiO 2 / Al 2 O 3 , ZrO 2 , LaAlO 3 on an interfacial layer of SrGe x , HfO 2 on an interfacial layer of Y 2 O 3 -doped GeO 2 , Y 2 O 3 on a GeO x interfacial layer, and HfO 2 with Al 2 O 3 to suppress HfO 2 -GeO x intermixing.…”

Progress in Materials for Microelectronics and Further Challenges

“…Neverhtless, recently new perspectives for use of this material have been demonstrated [1], [2], due to the high mobility of carriers.…”

Conductance of Threading Dislocations in InGaAs/Si Stacks by Temperature-CAFM Measurements

“…In HEMTs, TDs increase reverse gate leakage current and frequency related noise (affecting, for example, low-noise amplifiers [3]) and reduce drain saturation current, peak transconductance, off-state breakdown voltage and cutoff frequency [3]. In InGaAs nMOSFETs, TDs severely reduce carrier mobility [6], [7], affecting I ON and V TH and limiting drive current. Therefore, monitoring the TDs' contribution/effect to the charge transport through the III-V channels is critical for controlling/improving device characteristics [3], [7].…”