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Indium Phosphide (InP): Advantages and Disadvantages

semiconductor indium phosphide inp high frequency optoelectronic

This page explores the pros and cons of Indium Phosphide (InP), a semiconductor material. It highlights the benefits and drawbacks associated with its use.

What is Indium Phosphide (InP)? - An Introduction

  • Indium phosphide is a binary semiconductor composed of indium and phosphorus.
  • It possesses a face-centered cubic crystal structure, similar to GaAs and other III-V semiconductors. (See Figure 1)
  • The preparation of indium phosphide typically occurs at 400°C through the reaction of white phosphorus and indium iodide.

Indium Phosphide (InP) crystal structure

  • InP is used in high-frequency electronics, especially at high power levels.
  • When combined with InGaAs, it can form pseudomorphic HBTs (Heterojunction Bipolar Transistors) that can operate at frequencies up to 604 GHz.
  • It’s also crucial in manufacturing optoelectronic devices and photonic ICs for telecommunication systems.

Here are some key properties of Indium Phosphide (InP):

  • Band gap: 1.34 eV
  • Structure: Zinc blende
  • Electron mobility: 5400 cm2/(V*s) at 300 K
  • Thermal conductivity: 0.7 W/(cm*K) at 300 K
  • Refractive index (nD): 3.1 (infrared)

Benefits or Advantages of Indium Phosphide (InP)

Here are the key advantages of using Indium Phosphide:

  • Superior Electron Velocity: InP boasts a much higher electron velocity compared to silicon (Si) and gallium arsenide (GaAs), approximately 5 times greater.
  • Direct Band Gap: This property makes InP efficient for light emission and absorption.
  • Lower Base Sheet Resistance: Offers about 20 times lower resistance.
  • Higher Base Electron Diffusivity: Exhibits about 5 times higher electron diffusivity.
  • Higher Breakdown at Same fT: Demonstrates about 4 times higher breakdown.

Drawbacks or Disadvantages of Indium Phosphide (InP)

Despite its advantages, InP also has some limitations:

  • Limited Scaling: Currently, production is only scaled to around ~1 µm.
  • Emitter Issues: Suffers from large emitters and poor emitter contact.
  • Low Current Density: Exhibits a low current density, approximately 2 mA/µm2.
  • High Collector Capacitance: Has a high collector capacitance.
  • Non-Planar Device with Low Yield: Manufacturing processes often result in non-planar devices and lower yields.
  • Low Integration Scales: Integration scales are generally low.